Unlike the earlier car, the 18 was designed quickly; the time between its initial conception and its actual launch date was only eighteen months, primarily due to the fact that the 18 was based upon the 12's underpinnings.

[5] This experimental fuel efficient concept car, powered by a 1.1 L engine from the R5, featured then state-of-the-art microcomputer microprocessor, an array of specialised sensors, an electronically controlled carburettor, continuously variable automatic transmission, as well as aerodynamics and use of lightweight materials.

[12] This model was mechanically similar to the Renault 20 Diesel, and was equipped with a 2068 cc (126.2 cu in) engine (rated at 49 kW (66 PS)), negative offset front suspension, and larger four-stud wheels.

[14] Features included a five-speed gearbox, negative offset front suspension, four-stud alloy wheels, rear spoiler, dashboard and interior fittings from the Renault Fuego.

However, it soon had to compete with newer and quicker performance versions of the Vauxhall Cavalier (Opel Ascona) and Ford Sierra.

[12] Model-specific changes included the available option of a five-speed gearbox on the TL; the GTL received an "economy-tune" 73 PS (54 kW) version of the 1647 cc (100.5 cu in) engine, as well as a five-speed gearbox, higher final drive ratio, electronic ignition and an "economizer" gauge.

Limited to 5,200 examples (1,500 in the UK), it had a special black over silver two-tone paint and numerous luxury equipment such as alloy road wheels and a plusher interior.

Included were central locking, radio, and a choice of four colour schemes, with a total of 14,000 units (8,000 for France and 6,000 for the rest of Europe).

The grille was changed and all models gained a front air dam, while the saloons also received a standard rear spoiler.

The R18 Estate ("Break" in French-speaking countries, Argentina, and some other markets) was only available in TL, LS, and TS model variations, except in Australia where all Australian-assembled Renault 18s, sedans and station wagons, were GTS.

18i The station wagons provided comfortable seating for five, as well as featuring a folding rear bench seat that offered up to 65.5 cubic feet (1.85 m3) of cargo area with a 5.5-foot-long (1.68 m) flat floor and this carrying capacity was assisted by variable rate rear coil springs with long travel shock absorbers.

Modifications for the U.S. market included more stringent emissions controls, larger bumpers designed to withstand 5-mile-per-hour (8 km/h) impacts, two-tone paint, and uncovered sealed-beam headlights, as well as different hubcaps and interior trim.

[26] Being fuel injected, the four-door and the station wagon (called "Sportswagon"; the middle "s" was later dropped) were sold by AMC dealers as the Renault 18i beginning with the 1981 model year.

[29] When introduced, the fuel injected (Bosch L-Jetronic), 1647 cc straight-four offered 82 hp (61 kW) at 5500 rpm in federalized trim.

[26] The three-wand setup was replaced by a more traditional two-stalk solution for operating lights, wipers, and indicators.

[30] Period reviewers also commented on an improved quality feel vis-à-vis earlier model years.

The Deluxe has aerodynamic hubcaps while the sporty Touring has alloy wheels and the 18 Turbo's contrasting graphics along tha flanks.

[32] The Renault 18 was also built in Argentina, Colombia, Uruguay, and Venezuela, with some locally developed differences such as a larger, more powerful engine.

The TX was the initial 1981 model, featuring the Douvrin 2.0 L four-cylinder powerplant with 99 hp (73 kW), a first for a production 18 worldwide.

During 1982 the GTX was added to the lineup, featuring a fifth gear, air conditioning, and an engine upgraded to produce 103 hp (76 kW).

Towards the end of 1982 the 18 Break entered local production, in either TX or GTX trim, and the lower cost GTL sedan was added to the lineup.

This model received the 1.4-litre engine familiar from the European market, producing 77 hp (57 kW), and a five-speed transmission.

After local production ended, an imported 2.2-litre version called the Super GTX was available until replaced by the Renault 21 in 1989.

Two-speed wipers Intermittent screen wipe Electric screen washers Volt meter Engine coolant temperature gauge Fuel gauge Six-figure mileage recorder Trip recorder Handbrake warning light Defective front brake discs warning light Day/night position for interior rear view mirror Rheostat for adjusting brightness of dashboard lights Illuminated ashtray, heater panel, boot and glove box Heated rear screen Anti-dazzle headlight adjustment Adjustment for direction of headlight beam Cigarette lighter Driver's side sun visor Passenger's side sun visor Vanity mirror in passenger's side sun visor Full carpeting Cloth upholstery Front armrests with grab handles Rear armrests Ashtrays in the rear doors Childproof rear door locks Passenger's side interior courtesy light Front door pockets Center console incorporating coin tray Reclining front seats Loudspeakers in front doors Foam-filled steering wheel H4 iodine headlights Quartz clock Velour upholstery Styled wheels Driver's side interior courtesy light Map reading light for front seat passenger Remote-adjustable driver's side door mirror Rear fog lights Headlight wash/wipe system Pre-installation radio equipmentShock absorbent bumpers Adjustable front seat head restraints Black rubber protective side mouldings Foam-filled steering wheel H4 iodine headlights Quartz clock Velour upholstery Styled wheels Driver's side interior courtesy light Map reading light for front seat passenger Electric front windows Central locking A total of 2,028,964 Renault 18s were built in France alone.

The last Argentinian Renault 18 rolled off the production line in 1993, after a total of 132,956 units were built in Argentina alone.

Sales were initially strong, peaking at over 30,000 in 1980 when it was the tenth best-selling car in the UK and the most popular foreign model; but declined over the next few years as new competitors arrived from Ford, Vauxhall, and British Leyland.