Porsche 928

The Porsche 928 was a sports-GT car sold by Porsche AG of Germany from 1978 to 1995. Originally intended to replace the company's iconic 911, the 928 attempted to combine the power, poise, and handling of a sports car with the refinement, comfort, and equipment of a luxury sedan to create what some Porsche executives thought would be a vehicle with wider appeal than the compact, quirky and sometimes difficult 911.

Since its inception in 1949, Porsche has manufactured only six front-engined models, four of which were coupes, including the 928. The car has the distinction of being the company's only coupe powered by a front-mounted V8 engine, and the company's first mass-produced V8 powered model.

During 1983 the 928S was the fastest car sold in North America, with a top speed of 146 mph (235 km/h).

Conception[]

By the late 1960s, Porsche had changed significantly as a company, and executives including owner Ferdinand Porsche were playing with the idea of adding a luxury touring car to the line-up. Managing Director Ernst Fuhrmann was also pressuring Ferdinand to approve development of the new model in light of concerns that the current flagship model at the time, the 911, was quickly reaching its maximum potential where it could soon no longer be improved upon. Slumping sales of the 911 seemed to confirm that the model was approaching the end of its economic life cycle. Fuhrmann envisioned the new range-topping model as being the best possible combination of a sports coupe and a luxury sedan, something well equipped and comfortable enough to be easily driven over long distances that also had the power, poise and handling prowess necessary to be driven like a sports car. This set it apart from the 911, which was a pure sports car.

Ordered by Ferry Porsche to come up with a production-feasible concept for his new model, Fuhrmann initiated a design study in 1971, eventually taking from the process the final specs for the 928. Several drivetrain layouts were considered during early development, including rear and mid-engined designs, but most were dismissed because of technical and/or legislative difficulties. Having the engine, transmission, catalytic converter(s) and exhaust all cramped into a small rear engine bay made emission and noise control more difficult, something Porsche was already facing problems with on the 911 and wanted to avoid. After deciding that the mid-engine layout didn't allow enough room in the passenger compartment, a front engine/rear wheel drive layout was chosen. Porsche also may have feared that the U.S. government would soon ban the sale of rear-engined cars in response to the consumer concern over safety problems with the rear-engined Chevrolet Corvair. The Corvair's alleged safety issues were famously detailed in the book Unsafe at Any Speed by consumer advocate Ralph Nader.

Porsche engineers wanted a large-displacement motor to power the 928, and prototype units were built with a 5.0 L V8 producing close to 300 hp (220 kW). Ferdinand Piëch wanted this car to use a 4.6 liter V10 with 88 mm bore spacing based upon Audi's five-cylinder engine. This five-cylinder is a derivative of the Volkswagen Golf EA827 engine, basically a four with another cylinder added. Several members of the Porsche board objected; their official objection was because they wanted Porsche AG to maintain some separation from Volkswagen. The possible reason was that they didn't want their crowning car to be powered by a variant of the lowly VW Golf engine. Interestingly, this same proposed engine [albeit with greater displacement] was eventually built and installed in a production sports car— the Lamborghini Gallardo. To this day, no Porsche has ever used an EA827-based engine. Until 2011 they used a version of the VW VR6 engine in the Cayenne [955], but that motor is not related to the EA827 design.

The first two running prototypes of Porsche's M28 V8 used one four-barrel carburetor, but this was just for initial testing. The cars were sold with the planned Bosch K-Jetronic fuel injection system. When increasing concern within the company over the pricing and availability of fuel during the oil crisis of the 1970s became an issue of contention, smaller engines were considered in the interest of fuel economy. A push began for the development of a 3.3 L 180 hp (130 kW) powerplant they had drawn up specs for, but company engineers balked at this suggestion. Both sides finally settled on a 4.5 L, SOHC 16-valve V8 producing 240 PS (180 kW; 240 hp) (219 hp (163 kW) in North America), which they considered to have an acceptable compromise of performance and fuel economy.

The finished car debuted at the 1977 Geneva Motor Show before going on sale later that year as a 1978 model. Although it won early acclaim for its comfort and power, sales were slow. Base prices were much higher than that of the previous rangetopping 911 model and the 928's front-engined, water-cooled design put off many Porsche purists.

Fuhrmann's replacement, Peter Schutz, decided that the models should be sold side by side, feeling that the 911 still had potential in the company's line-up. Legislation against rear-engined vehicles also did not materialize. Although the 928 developed an avid fan following, it never sold in the numbers Fuhrmann had originally predicted and was discontinued in 1995.

Design[]

The 928 featured a large, front-mounted and water-cooled V8 engine driving the rear wheels. Originally displacing 4.5 L and featuring a single overhead camshaft design, it produced 219 hp (163 kW/222 PS) for the North American market and 237 hp (176 kW/240 PS) in other markets. Porsche upgraded the engine from mechanical to electronic fuel injection in 1980 for US models, although power remained the same. This design marked a major change in direction for Porsche (started with the introduction of the Porsche 924 in 1976), whose cars had until then used only rear- or mid-mounted air-cooled flat engines with four or six cylinders.

Porsche utilized a transaxle in the 928 to help achieve 50/50 front/rear weight distribution, aiding the car's balance. Although it weighed more than the difficult-to-handle 911, its more neutral weight balance and higher power output gave it similar performance on the track. The 928 was regarded as the more relaxing car to drive at the time. It came with either a five-speed dog leg manual transmission, or a Mercedes-Benz-derived automatic transmission, originally with three speeds, with four-speed from 1983 in North America and 1984 in other markets. More than 80% had the automatic transmission. Exact percentage of manual gearbox cars for entire production run is not known but its believed to be between 15 and 20%.

The body, styled by Wolfgang Möbius under guidance of Anatole Lapine, was mainly galvanized steel, but the doors, front fenders, and hood were aluminum in order to make the car more lightweight. It had a substantial luggage area accessed via a large hatchback. The new polyurethane elastic bumpers were integrated into the nose and tail and covered in body-coloured plastic; an unusual feature for the time that aided the car visually and reduced its drag. Porsche opted not to offer a convertible variant but several aftermarket modifiers offered convertible conversions, most notably Carelli, based in Orange County, CA. The Carelli conversions were sold as complete cars, with the conversion doubling the price of the car. A reported 12 units were made.

The 928 qualified as a 2+2, having two small seats in the rear. Both rear seats could be folded down to enlarge the luggage area, and both the front and rear seats had sun visors for occupants. The rear seats are small due to the prominent transmission hump [the front seats have leg room like a front drive car due to the rear transmission], and are only suitable for children, or for typical adults on a short trip. The 928 was also the first vehicle in which the instrument cluster moved along with the adjustable steering wheel in order to maintain maximum instrument visibility.

The 928 included several other innovations such as the "Weissach Axle", a simple rear-wheel steering system that provides passive rear-wheel steering while cornering, and an unsleeved, silicon alloy engine block made of aluminum, which reduced weight and provided a highly durable cylinder bore.

Porsche's design and development efforts paid off during the 1978 European Car of the Year competition where the 928 won ahead of the BMW 7-series and the Ford Granada. The 928 is the only sports car so far to have won this competition, where the usual winners are mainstream hatchbacks and sedans/saloons from major European manufacturers. This is regarded as proof of how advanced the 928 was compared to its contemporaries.

Styling changes[]

Styling was the same from 1978 through 1979 and the body lacked both front and rear spoilers. From 1980 (1983 in North America) through 1986, front and rear spoilers were present on "S" models, rear spoilers were integrated into the hatch. From 1987 through 1995, the front spoiler is integrated into the nose and the rear spoiler became a separated wing rather than an integrated piece, and side skirts were added. The rear tail-light configuration was also different from previous versions. GTS model had wider rear fenders added to give more room for 9" wide wheels.

Another easily noticeable visual difference between versions is the style of the rims. Early 928s had 15" or 16" "phone dial"-style rims, while most 1980s 928s had 16" slotted "flat discs", CSs, SEs and 1989 GTs had 16" "Club Sport", later GTs had 16" "Design 90" style which were also option on same period S4s, the GTS used two variations of the 17" "CUP" rims.

Later variants[]

Porsche introduced a refreshed 928 S into the European market in 1979 model year, although it was summer of 1982 and MY 1983 before the model reached North America. Externally, the S wore new front and rear spoilers and sported wider wheels and tires than the older variant, but the main change for the 928 S was under the hood, where a revised 4.7 L engine was used. European versions debuted with 300 PS (221 kW/297 hp), and were upgraded to 310 PS (228 kW/306 hp) for 1984 model year, though it is rumored [and proven on chassis dynamometers] that they typically made around 330 hp. From 1984 to 1986, the ROW (Rest of World) S model was called S2 in UK. These cars used Bosch LH-Jetronic fuel injection and purely electronic Bosch ignition, the same systems used on the later 32-valve cars, though without the pollution controls. North American-spec 1983 and 1984 S models used, among other differences, smaller valves, milder camshafts, narrower intake manifolds, and additional pollution equipment in order to meet emissions regulations, and were limited to 234 hp (174 kW/230 PS) as a result.

As the faster ROW or "Euro" model was not available in the United States and Canada during the first three years of its existence, a "Competition Group" option was created to allow North American customers to have an S model lookalike with spoilers, 16" flat disc wheels, sport seats, sport springs and Bilstein shocks. Customers could specify paint and interior colors the same way as on a normal 928. The package was available in 1981 and 1982 model years and was canceled in 1983 when the S model became available for these markets. Many cars have had S model features added by subsequent owners, making original "Competition Group" cars difficult to distinguish without checking option codes.

In 1982 model year, two special models were available for different markets. 205 "Weissach Edition" cars were sold in North America. Unusual features were champagne gold metallic paint, matching brushed gold flat disc wheels, two-tone leather interior, a plaque containing the production number on the dash and the extremely collectible three-piece Porsche luggage set. It's believed these cars were not made with S spoilers even though these were available in U.S. during this time period as part of the "Competition Group" option. The "Weissach Edition" option was also available for the US market 911 in 1980 model year and 924 in 1981 model year.

140 special "50th Jubilee" 928 S models were available outside the U.S. and Canada to celebrate the company's 50 year existence as a car manufacturer. This model is also sometimes referred to as the "Ferry Porsche Edition" because his signature was embroidered into the front seats. It was painted meteor metallic and fitted with flat disc wheels, wine red leather and special striped fabric seat centers. Similar 911 and 924 specials were also made for ROW markets.

Porsche updated the North American 928 S for 1985, replacing the 4.7 L SOHC engine with a new 5.0 L DOHC unit sporting four valves per cylinder and producing 288 hp (215 kW/292 PS). Seats were also updated to a new style. These cars are sometimes unofficially called S3 to distinguish them from 16-valve ROW "S" models. European models kept a 4.7 L engine, which was somewhat more powerful as standard, though the American-spec 32-valve engine together with catalytic converters became an option in some European countries and Australia for 1985. In 1986, revised suspension settings, larger brakes with 4-piston calipers and modified exhaust was installed on the 928S, marking the final changes to old body style cars. These were straight from the 928S4, which was slated to debut a few months later. These changes came starting from VIN 1001, which means that the first thousand '86's had the old brakes, but later cars had the later systems. This later 1986 model is sometimes referred to as a 1986¹⁄₂ or 1986.5 because of these changes. The name is a little misleading as more than 3/4 of the 1986 production had these updates.

The 928 S4 variant debuted in the second half of 1986 as a 1987 model, an updated version of the 5.0 L V8 for all markets producing 320 PS (235 kW/316 hp), sporting a new single-disc clutch in manual gearbox cars, larger torque converter in automatics and fairly significant styling updates which gave the car a cleaner, sleeker look. S4 was much closer to being a truly world car than previous models as only major differences between ROW and US models were instrumentation in either kilometers or miles, lighting, front and rear bumper shocks and the availability of catalytic converters in many ROW markets. The Australian market version was only one with different horsepower rating at 300 PS (221 kW/296 hp) due to preparation for possible low grade fuel. Even this was achieved without engine changes.

A Club Sport variant which was up to 100 kg (220 lb) lighter became available to continental Europe and U.S. in 1988. This model was watered down version of 1987 factory prototype which had lightened body. Also in 1987 the factory made four white lightened manual gearbox S4 models for racecar drivers who were on their payroll at the time. These were close to same as later actual Club Sport models and can also be considered prototypes for it. An SE (sometimes called the S4 Sport due to model designation on rear bumper), a sort of halfway point between a normally equipped S4 and the more race-oriented Club Sport, became available to the UK. It's generally believed these Porsche Motorsport-engined cars have more hp than the S4. They utilize parts which later became known as GT pistons, cams, engine ECU programs and a stronger, short geared manual gearbox. The automatic gearbox was not available.

For the 1989 model year, a visible change inside was digital trip computer in dashboard. At the same time Australian models received the same 320 PS (235 kW/316 hp) engine management setup as other markets. Porsche debuted the 928 GT in the late winter 1988/89 after dropping the slowly selling CS and SE. In terms of equipment, the GT was like the 928 SE, having more equipment than a Club Sport model but less than a 928 S4 to keep the weight down somewhat. It had the ZF 40% limited-slip differential as standard like the Club Sport and SE before it. Also like the CS and SE, the GT was only available with a manual gearbox. ROW 1989 CS and GT wheels had an RDK tire pressure monitoring system as standard. This was also optional for the same year ROW S4. For 1990 model year Porsche made RDK and a 0-100% variable ratio limited-slip called PSD (Porsche SperrDifferential) standard in both GT and S4 models for all markets. This system is much like the one from the 959 and gives the vehicle even more grip. In 1990 the S4 was no longer available with a manual gearbox.

The S4 and GT variants were both cut at the end of 1991 model year, making way for the final version of the 928. The 928 GTS came for sale in late 1991 as a 1992 model in Europe and in spring of 1992 as an early 1993 model in North America. Changed bodywork, larger front brakes and a new, more powerful 5.4 L, 350 PS (257 kW/345 hp) engine were the big advertised changes; what Porsche wasn't advertising was the price. Loaded GTS models could eclipse US$100,000 in 1995, making them among the most expensive cars on the road at the time. This severely hampered sales despite the model's high competency and long standard equipment list. Porsche discontinued the GTS model that year after shipping only 77 of them to the United States. Total worldwide production for all years was a little over 61,000 cars.

Second-hand models' value decreased as a result of generally high maintenance costs due largely to spare parts that are expensive to manufacture. The earliest versions, however, especially those models with the Bosch K-Jetronic (CIS) injection system, have few electronic components and therefore can be repaired more easily provided spare parts can be found. Parts suppliers supported by various enthusiasts exist especially in the United States.

The GTS model has retained a high value however, and as of 2006 the price for all variants is apparently starting to creep upwards (Classic Motorsports, March, 2006 issue, p. 38).

With the release of the Cayenne SUV, Porsche has met with renewed success with a front-engined, V8-powered model. The company's 2005 announcement that a new V8-powered 4-door grand tourer model called Panamera would be launched in 2009 fueled rumors and fan speculation of a reborn 928. Although the Panamera will be a 4-door model, Road and Track magazine published a speculative piece in their April 2006 issue regarding the possibility of a new, 928-esque coupe that may debut on a shortened version of the Panamera's platform sometime around 2011 or 2012 model year. Although feasible, this is pure speculation as of 2006. The article seemed to indicate a re-use of the 928 nameplate although Porsche's recent tendency to give non-numerical names to their vehicles and a desire to separate the vehicle from past models may preclude the possibility of calling the vehicle 928.

928 evolution[]

The evolution of the 928 during its 18 years of production was quite subtle. The tables below show the major differences, which were made to the nose, tail, interior, engine, and wheels.

1978[]

Model designation: 928
Engine displacement: 4.5 L (approx. 275 cid)
Valves: 16
Bosch K-Jetronic injection
Power (DIN): 240 PS (177 kW) / 219 hp (163 kW) (North America)
Torque: 363 N·m (268 ft·lbf)

1979[]

Model designation: 928
Power: 240 PS (177 kW) / 219 hp (163 kW) (North America)
Changes:
- Battery box integrated as part of the body, was previously mounted to gearbox.
- Gearbox shocks deleted.

1980[]

Model designation: 928 S (928 in North America)
Engine displacement: 4.5 L / 4.7 L (S model)
Valves: 16
Power: 240 PS (177 kW) (4.5) / 300 PS (221 kW) (4.7 S) 229 HP (167 kW) for North America only.
Changes:
- Bosch L-Jetronic injection in North America.
- Addition of "S" model worldwide (not available in North America until 1983)
- Front & rear spoilers (S model)
- Manual gearbox changed during model year requiring shorter torque tube.
- "S" brakes into use during model year in all wordwide models (except North America).

1981[]

Model designation: 928 S (928 remains in North America)
Changes:
- "Competition Package" option available to US market.

1982[]

Model designation: 928 S (928 in North America)
Changes:
- Vibration damper added into torque tube between 2nd and 3rd support bearing on manual gearbox cars and behind 2nd bearing on automatics.
- Reverse gear lock added to manual gearbox.
- 140 "50th Jubilee" 928 S made for worldwide markets.
- "S" brakes available in US models.
- 205 "Weissach Edition" model for US market.
- 4.5 "L" model dropped from production at end of 1982 model year.
- US "Competition Package" option dropped from production at end of 1982 model year.

1983[]

Model designation: 928 S
Weight: 1500 kg (3300 lb)
Engine displacement: 4.7 L
Power: 300 PS (221 kW) / 239 hp (174 kW) (for North America)
Changes:
- North American introduction of "S" model. The Non-S 928 (4.5 L) model dropped.
- New style hydraulic motor mounts.
- Engine shocks deleted at same time.
- 4-speed automatic transmission for North America.
- Car body and torque tube changed to accommodate longer gearbox.

1984[]

Model designation: 928 S (928 S2 in United Kingdom)
Weight: 1500 kg (3300 lb)
Engine displacement: 4.7 L
Valves: 16
Power: 310 PS (228 kW) / 239 hp (174 kW) for North America.
Changes:
- "S" model renamed "S2" in UK market.
- Bosch LH-Jetronic injection and 4-speed automatic transmission added (previously only available in North America)
- Torque tube shortened like on US model in previous year.
- EZF ignition system using dual distributors makes debut. This allows higher 10.4:1 compression and increased torque.
- Compression change done in middle of model year once 10.0:1 compression ratio resulting piston stock were used up in production.
- ABS brakes optional for the first time in Porsche, standard on German model.
- At 146 mph (235 km/h) US model top speed, Porsche boldly claims the 928 S to be "the fastest street legal production car sold in the US".
- Important safety related change to front suspension lower ball joints on all cars in September 1983.

1985[]

Model designation: 928 S / 928 S2 (UK)
Weight: 1500 kg (3300 lb)
Engine displacement: 4.7 L / 5.0 L (305 cid) for North America
Valves: 16 (32 in North America)
Power: 310 PS (306 hp, 228 kW) (worldwide) / 292 PS (288 hp, 215 kW) (for North America) / 275 PS (272 hp, 202 kW) (4.7 L) for (Sweden and Switzerland)
Changes:
- New 5.0 liter 32-valve LH-Jetronic injection and EZF ignition 288 hp engine for US market.
- Top speed (US model) is now in excess of 250 km/h (155 mph).
- US model with lowered 9.3:1 compression ratio. 16-valve engine (10.4:1 c/r) for Sweden and Switzerland.
- Compression change was done with different shape piston tops. Coupled only with automatic transmission.
- Engine number is same M28/22 as in high compression 16-valve engines.
- Only outside indication for different pistons is option code "M151".
- LH-Jetronic control box design changed in international markets.
- New style front seats. Redesigned more modern looking door panels when multi speaker stereo was ordered.
- Gearbox synchromesh changed to Borg Warner design and shorter gear lever, improving driveability on manual transmission cars.
- Shims left out from front end of torque tube drive plate in automatic cars, this sometimes cause engine thrust bearing failures.
- Radio antenna moved to embedded windshield wire.

1986[]

Model designation: 928 S / 928 S2 (UK)
Engine displacement: 4.7 L / 5.0 L (North America)
Valves: 16 (32 for North America)
Power: 310 PS (306 hp, 228 kW) (worldwide) / 292 PS (288 hp, 215 kW) (for North America) / 275 PS (272 hp, 202 kW) (4.7 L) (for Sweden and Switzerland)
Changes:
- Lowered 9.3:1 compression ratio 32-valve engine optional for some international markets along with catalytic converter, standard in Australia. Compression change was done with different shape piston tops.
- Lowered compression ratio of 9.3:1 16-valve engine for Sweden and Switzerland. Compression change was done with different shape piston tops. Only paired with automatic transmission. Engine number is same M28/22 as in high compression 16V engines. Only outside indication for different pistons is option code M151.
- "S4" suspension package and Brembo brakes for 1986 models (from VIN 1001 and November 1985 onwards in North America). No US models made with VIN ending between 0938 and 1000 due to parts change.
- ABS brakes became standard for all markets during model year production.

1987[]

Model designation: 928 S4
Weight: 1590 kg (3500 lb)
Engine displacement: 5.0 L
Valves: 32
Power: 320 PS (316 hp, 236 kW) / 300 PS (296 hp, 221 kW) for Australia.
Changes:
- Different style pistons, cylinder heads, camshafts, intake and larger intake valves compared to earlier 5.0 L engines.
- Nominal static compression ratio 10.0:1 (True ratio between 9.4:1 and 10.0:1, depending on parts used).
- Cylinder head studs used in all earlier engines replaces with bolts making it easier to remove heads while engine is in engine bay.
- Updated LH-Jetronic injection and ignition changed to EZK system, two knock sensors added to engine. Single disk clutch on manual transmission cars, larger torque converter on automatics.
- Modified front brake calipers into use with 2 mm diameter increase for large piston. Cars sold to U.S., Canada, Australia and Arabic countries got new parts once remaining old design caliper stock was used up.
- New style front & rear bumpers and rear wing spoiler.
- Redesigned front and rear bumper light assemblies.
- Body changed compared to earlier models to accommodate larger rear lamps, rear seat area modified to give room for new torque converter.
- Upwards folding rear spoiler and piston oil squirters in engine block on early cars only.
- Different horsepower rating for Australia due to different ignition map used because of possible low grade fuel.

1988[]

Model designation: 928 S4 / 928 CS / 928 SE (UK)
Engine displacement: 5.0 L
Valves: 32
Power: 320 PS (316 hp, 236 kW) (S4, CS and SE) / 300 PS (296 hp, 221 kW) (S4) for Australia
Changes:
- Lighter 928 CS "Club Sport" version available in Continental Europe and USA, 928 SE (S4 Sport) in UK.
- Only model year for "CS" (USA) and "SE" (UK). Elsewhere, "CS" uses different VIN sequence than normal "S4".
- Stronger torque tube with 3 mm thicker center shaft for automatic transmission.
- Pistons with strengthened skirt into use in February 1988.
- Oil drainage improved in piston skirts.

1989[]

Model designation: 928 S4 / 928 CS / 928 GT (no "CS" model in USA or UK)
Engine displacement: 5.0 L
Valves: 32
Power: 320 PS (316 kW) (S4) / 330 PS (326 hp, 243 kW) (GT)
Changes:
- February 1989, manual transmission-only "928 GT" debuts as a more sporting version (all markets).
- Digital trip computer/warning system added to dashboard, ignition circuit monitor system added.
- For Australian cars same ignition maps resulting same horsepower rating as in other markets.
- North America manual tranmission model now uses same shorter final drive ratio as used elsewhere, to simplify production.
- RDK tyre pressure monitoring system optional on S4, standard on CS and GT.
- Thicker cylinder head casting taken into use early in model year to strengthen head against cracking. Longer head bolts needed because of the change.
- Modified front brake calipers with improved seals taken into use early in model year.
- 928 CS into same VIN sequence as 928 S4. Model dropped from production during the model year at the end of 1988.

1990[]

Model designation: 928 S4 / 928 GT
Engine displacement: 5.0 L
Valves: 32
Power: 320 PS (316 kW) (S4) / 330 PS (326 hp, 243 kW) (GT)
Changes:
- GT pistons into use in S4 also resulting true 10.0:1 compression ratio for all engines.
- RDK tyre pressure monitoring system standard on all cars. Computer controlled 0-100% PSD locking differential added to both models.
- S4 no longer available with manual gearbox.
- Dual airbags now standard across all Porsche models in U.S. Driver and front passenger airbag optional in LHD ROW cars, only drivers side bag available in RHD markets.

1991[]

Model designation: 928 S4 / 928 GT
Engine displacement: 5.0 L
Valves: 32
Power: 320 PS (316 kW) (S4) / 330 PS (326 hp, 243 kW) (GT)
Changes:
- Improvements to cooling in exhaust side at cylinder heads, steering rack, power steering pump, soundproofing, front cooling flaps deleted, new style shift knob with integrated leather booth in manual gearbox cars, etc.
- Temperature sensors for ignition circuit monitor system moved from #4 and #8 cylinders to #3 and #7 cylinders to improve their efficiency.
- Check engine warning light added to all US models due to California regulatory demands.
- Two airbags as standard in LHD models during model year production for most markets.

1992[]

Model designation: 928 GTS
Engine displacement: 5.4 L
Valves: 32
Power: 350 PS (345 hp, 257 kW)
Changes:
- Engine displacemente increases to 5.4 L due to longer stroke crankshaft and different compression height
- 10.4:1 compression ratio pistons
- Milder camshafts for emission purposes
- Bodywork updated with flared rear fenders and so-called "cup" mirrors.
- "Big Black" front brakes, significantly larger than "S4" version.
- Stronger manual gearbox with differential driven oil pump and front-mounted oil cooler.
- GTS became available in North America at January 1992 as early 1993 model with later model year VIN. These cars use same parts as 1992 models and can be differentiated from true 1993 US models with separate VIN sequence and option code M718.

1993[]

Model designation: 928 GTS
Engine displacement: 5.4 L
Valves: 32
Power: 350 PS (345 hp, 257 kW)
Changes:
- Cylinder block lower half studs replaced with bolts.
- Engine piston rings changed to limit oil consumption and pistons changed to strengthen skirt area.
- Minor update to gearbox clutch.
- Air conditioner refrigerant changed to R-134a.
- Driver side airbag standard in RHD cars, passenger side airbag not available in them.

1994[]

Model designation: 928 GTS
Engine displacement: 5.4 L
Valves: 32
Power: 350 PS (345 hp, 257 kW)
Changes:
- Cabin pollen filter added.
- Dynamic kickdown for automatic transmission models.
- Wheel design changed to "Cup II", RDK deleted at same time.
- First 19 US models were made already in spring of 1993, months before when normal model year change occurs in July/August. These M718 option cars still used previous model year parts like Cup I wheels and do not have 1994 model year updates despite using same 1994 VIN sequence.
- Connecting rods changed to stronger design part in middle of model year.

1995[]

Model designation: 928 GTS
Engine displacement: 5.4 L
Valves: 32
Power: 350 PS (345 hp, 257 kW)
Torque: 500 N·m (369 ft·lbf)
Changes:
- Special model available in some markets containing wider front fenders made out of steel and 8" wide front wheels.
- (Only available with automatic gearbox) "Iris blue" metallic and "Amazon green" metallic color with Classic grey leather interior.

Special versions[]

Porsche 942[]

The Porsche 942 was a special edition 928 presented by the company as a gift to Ferry Porsche on his 75th birthday in 1984. Its also known by name 928-4, 928S. It featured 10 in (254 mm) longer wheelbase than normal 928 production model, including an extended roof above the rear seats to better accommodate tall passengers, at the time very advanced projector headlights, the 5 liter 32-valve engine before it was introduced in US market, and S4 front and rear bumpers two years before they entered production.

"Study H50" Four-door 928 based prototype[]

Three years later, in 1987, the lengthened 928 that had been presented to the company's founder on his 75th birthday turned up as a "Feasibility Study", now with a second (rather narrow) set of doors, apparently opening in the same way as the doors on the twenty-first century Mazda RX-8. At the time "Study H50" appeared to sink with little trace, but two decades later, with the launch of the larger four-door Porsche Panamera, the 928 based four-door prototype from 1987 acquired greater significance.

928 long wheelbase specials[]

In 1986 Porsche together with tuning company AMG made few long wheelbase 928 specials. Unlike 942, these had normal 928 headlights. One was presented to American Sunroof Corporation (ASC) founder and CEO Heinz Prechter. ASC was later partly responsible of making Porsche 944 S2 cabriolets.

The Max Moritz 'Semi Works' 928 GTR[]

Porsche's Racing Department never officially entered or prepared a racing 928 for a pure works entry. Only once Porsche decided to make it obvious to the 911 enthusiasts that they usually tended to underrate the racing genes of the 928. Porsche then "arranged" this 928GTR to compete against the then dominant 911(993GTR) on the race track. In order not to offend sensibilities of their traditional 911/993GTR customers by officially challenging them with an outright Works - 928GTR, Porsche asked Max Moritz Racing, their longtime private racing partner from next door Reutlingen to enter this 928GTR Cup as a 'semi-works' car.

It didn't come as a surprise that the drivers were: Bernd Mayländer, Manuel Reuter (Porsche works pilots), also Harm Lagaay (then Head of Porsche's Design Studio). Vittorio Strosek sponsored MM with his Lightweight-Body-Parts and racing exhaust. The car was officially entered by Porsche-Club-Schwaben. Homologation minimum weight had to be, and actually is 1,370 kg (3,000 lb).

Lagaaij reports that the car was very competitive and able to hold most 964 CUP GTs down, although the engine was no more than fine-tuned after having been chosen from a set of high power output specimen in Weissach. In the last race of the season at Hockenheim a crank-bearing ran dry. As the car was supposed to race in 1995 as well, she was made ready to continue her successful competition in the 1995 season. A fresh engine was installed, selected from the same lot of high output engines and tuned as before. In 1995 Porsche's 928 production came to an end, and the car consequently was not raced in the new season.

The late Max Moritz himself then had her join his collection of historic cars. She was not put on the road again until after his death, when the family sold the car in October 2004 - with only 24500 km on the clock (Porsche-Weissach is the only documented owner).

All-aluminum 928[]

For the 1984 24 hours of Daytona, Porsche sent one of its experimental "All-aluminum" 928S to the Brumos Racing Team to be prepared with specific instruction not to modify the car in any way. Porsche wanted to promote the performance of the 928 to North America. The drivers Richard Attwood (GB), Vic Elford (GB), Howard Meister (USA) and Bob Hagestad (USA) were told to just "drive the car". During practice for the 24 hour race the drivers found the car to be somewhat unstable on the high banks of Daytona and wanted to add a rear wing to the car, Porsche said No. The Brumos team tinkered with the suspension set up to make the car more stable. The car finished in 15th overall and 4th in the GTO class. One driver stated in an interview later on, that was it not for a lengthy pit stop to fix some body damage, they would have finished in the top 5 overall. The car was then returned to Porsche and is now in the Porsche Museum.

A 928S from Raymond Boutinaud also competed at the 24 Hours of Le Mans in 1983 & 1984 with a 22nd place finish in 1984. The same car also competed in 1000k races at Spa, Brands Hatch and Silverstone in 1984, but with little success. It has been rumored that the Raymond Boutinaud 928S was also an "all-aluminum" car from Porsche but that has been unfounded.

Bonneville[]

On August 7, 1986 American racing driver Al Holbert set a speed record at Bonneville in a pre-production 928 S4. This 928 would turn 171.110 mph in the flying mile and 171.926 mph for the flying kilometer. In March of 1986, the same car reportedly did 180+ mph at Nardo, but the Bonneville run netted United States Auto Club official record "at the time" for International Category A, Group 2, Class 9, for normally aspirated vehicles. That made 1987’s 928 S4 the fastest non-turbocharged production car in the world.

Relationship with the 911[]

Some, mainly marque enthusiasts and other company outsiders, feel that the 911 was a better sports car than the 928, and cite that the 928 was marketed to a broader and somewhat different overall customer base to back their claims. These hark back to arguments made in 1964 when Porsche introduced the 911 as the successor to the 356, which was lighter, simpler and not nearly as "burdened" with luxury features as the incoming 911, but ultimately was proven to be the less competent car.

While it's true that Porsche marketed the 928 as a high performance GT car rather than a traditional sports car and that it was larger, heavier and much more luxurious than the contemporary 911, most sources, including factory insiders and the car's "father" Ernst Fuhrmann say that Porsche executives intended for the 928 to replace the 911 both as Porsche's flagship model and as the company's sportiest offering.

Aside from text sources and insider statements, the raw performance numbers further back these claims; the 928 was capable of easily out-accelerating every version of the 911 sold during its lifetime except the 964 generation 911 Turbo, a car difficult to extract the most from in track situations. In addition, the 928's predictable handling, aided by its superior 50/50 weight distribution, made it a competent on-track match for the 911 in nearly any real-world situation.

Rumored new 928[]

In some automotive magazines and web sites, such as Road & Track, Car and Driver, and TopSpeed.com, there have been endless rumors about a quite possible rebirth to a classic model that has been set aside, but not forgotten, in the Porsche archives - the 928. It has been reported that Porsche is planning a new sports coupe derived from the 928, and the Panamera.