The Lexus LS is a full-size luxury sedan that serves as the flagship model of Lexus, the luxury division of Toyota. Four generations of the sedan have been produced, all equipped with V8 engines and rear-wheel drive, although since 2006 all-wheel drive, hybrid, and long-wheelbase variants have also been offered. The original Lexus LS 400, the first Lexus to be developed, was introduced as the premium marque's debut model in September 1989. Subsequent redesigns included the second-generation LS 400 in November 1994, the LS 430 in January 2000, and the LS 460/LS 460 L series in 2006. A domestic-market version of the LS 400 and LS 430, badged as Toyota Celsior, was sold in Japan until the Lexus marque was introduced there in 2006. In 2006 (for the 2007 model year) the fourth-generation LS 460 debuted the first production eight-speed automatic transmission and an automatic parking system. In 2007, V8 hybrid powertrains were introduced on the LS 600h/LS 600h L sedans.

Development of the Lexus LS began in 1983 as the F1 project, the code name for a secret flagship sedan effort. The resulting sedan followed an extended five-year design process at a cost of over US$1 billion, and premiered with a new V8 engine and multiple luxury features. The Lexus LS was intended from its inception for export markets, and the Lexus division was formed to market and service the vehicle internationally. The original LS 400 debuted to strong sales, and was largely responsible for the successful launch of the Lexus marque. Each successive iteration of the vehicle has ranked as the best-selling flagship luxury sedan in the United States.

Since the start of production, each generation of the Lexus LS has been produced in the city of Tahara, Aichi, in Japan. In U.S. consumer publications, Lexus' flagship model is recognized as one of the most reliable vehicles ever built, having held the top ranking in J.D. Power and Associates' U.S. Vehicle Dependability Survey for fifteen consecutive years (1994–2009), and receiving Consumer Reports' highest rankings for vehicle dependability.

1st Generation

In late 1985, designers presented the first exterior study models to F1 management, featuring a sports car-like design with a low-slung hood and narrow front profile. By 1986, the sedan used a three box design with an upright stance, more prominent grille, and a two-tone body.Extensive modeling and wind tunnel tests resulted in a low drag coefficient for a conventional production vehicle of the time ( 0.29).[10] For the passenger cabin, materials selection tests evaluated 24 different kinds of wood and multiple types of leather for two years before settling on specific trim combinations. By 1986, the Lexus marque was created to support the launch of the flagship sedan, and the vehicle became known as the Lexus LS.Following eight design reviews, subsequent revisions, and over US$1 billion in development expenses, the final design for the production Lexus LS 400 (chassis code UCF10) was approved in May 1987 with design patents filed on May 13, 1987.

In January 1989, the LS 400 made its debut as a 1990 model at the North American International Auto Show, in Detroit, Michigan. U.S. sales began in September 1989, followed by limited exports to Australia, Canada, and the United Kingdom. The LS 400's new 4.0 liter 1UZ-FE 32-valve V8 engine, capable of 190 kilowatts (250 hp) and 353 newton metres (260 ft·lbf) of torque, was linked to a new four-speed automatic transmission with electronically controlled shifts. The chassis used an independent, double-wishbone suspension setup, and an air suspension system was optional. The LS 400's 0–100 kilometres per hour (62 mph) time was 8.5 seconds, and its top speed was 250 kilometres per hour (160 mph). Compared to the rival target BMW 735i (E32) and Mercedes-Benz 420 SE (W126), the LS 400 had a quieter cabin, with 58 dB at 100 kilometres per hour (62 mph); a higher top speed; a lower drag coefficient and curb weight; and it avoided the U.S. Gas Guzzler Tax.

The LS 400 was among the first luxury sedans to feature an automatic tilt-and-telescoping steering wheel with SRS airbag, power adjustable shoulder seat belts, and an electrochromic rear-view mirror.The five-passenger cabin included California walnut and leather trim, power-adjustable seats, and soft-touch controls. A back-lit electroluminescent gauge cluster featured a holographic visual effect, with indicator lights projected onto the instrument panel. The memory system stored the driver's seat, side mirror, steering wheel, and seat belt positions. Available luxury options included a Nakamichi premium sound system and an integrated cellular telephone with hands-free capabilities. The LS 400 further contained some 300 technological innovations to aid smooth operation and silence, including fluid-damped cabin fixtures, vibration-insulating rubber mounts, airflow fairings, and sandwich steel body panels.

In Japan, the launch of Lexus was complicated by Toyota's existing four domestic dealership networks at the time of its introduction. The Toyota Crown and Toyota Century were exclusive to Toyota Store locations. During the LS 400's development, local dealers' requests for a Japanese domestic market version had grown and a right-hand-drive Toyota Celsior-badged version was introduced shortly after the LS 400's U.S. debut, and introduced October 9, 1989 and only available at Toyopet Store locations.The Celsior, named after the Latin word for "supreme", was largely identical to the LS. Models came in either basic "A", upgraded suspension "B", or fully equipped "C" trim specifications. The Crown and the Crown Majesta, which appeared later in 1991, were only available at Toyota Store locations which carried Japan-only Toyota luxury models, like the Century.

Adding incentive for early U.S. sales was a base price of US$35,000, which undercut competitors by thousands of dollars and brought accusations of selling below cost from rival BMW. In December 1989, shortly after the LS 400's launch, Lexus ordered a voluntary recall of the 8,000 vehicles sold so far, based upon two customer complaints over defective wiring and an overheated brake light. All vehicles were serviced within 20 days, and the incident helped establish Lexus' customer service reputation. By 1990, U.S. sales of the LS 400 had surpassed those of competing Mercedes-Benz, BMW, and Jaguar models. Production of the first-generation LS 400 totaled over 165,000 units. Years after its introduction, the LS 400 remained a reliable choice for a used car, making Consumer Reports' 2007 list of recommended vehicles that regularly last 320,000 km (200,000 mi) or more with proper maintenance.