peaking in 1980 as the tenth best-selling car there with over 30,000 sales, but sales declined over the next few years in the face of new British-built competitors in the shape of the Ford Sierra, Vauxhall Cavalier, and Austin Montego. The first changes were announced for 1979 at the Paris Motor Show in October 1978. Rear-seat belts were now fitted as standard, and a manual choke replaced the automatic one with which the car had been launched. The station wagon as well as a new basic model, called simply the "Renault 18", were introduced. Also new for 1979, the 18 Automatic became a separate model (with GTL trim) rather than simply a transmission option. A year later, all production models were outfitted with a new alternator that included a built-in electronic regulator. In July 1980, the 18 Diesel model was added. This model was mechanically similar to the Renault 20 Diesel, and was equipped with a engine (rated at ), negative offset front suspension, and larger four-stud wheels. The diesel-engined 18s came in two trim levels: TD and GTD. The basic TD (which was available as both a saloon and estate) had a four-speed gearbox and the equipment level of the TS, while the GTD (which was exclusively available as a saloon) had a five-speed gearbox and an equivalent equipment level as the GTS. Power-assisted steering was optional on the GTD, while a five-speed gearbox was optional on the TD. Diesel model sales never reached thirty percent of the overall annual production. The 18 Turbo model was introduced in September 1980, borrowing from other Renault models. The 18 Turbo featured a engine rated at , five-speed gearbox, negative offset front suspension, four-stud alloy wheels, rear spoiler, dashboard and interior fittings from the Renault Fuego. A little later yet, a Turbodiesel version arrived; it had an version of the 2.1 L inline-four fitted to the TD/GTD and at the time it was the fastest car in its class. However, it soon had to compete with newer and quicker performance versions of the Vauxhall Cavalier (Opel Ascona) and Ford Sierra. Model year 1982 saw the introduction of several changes to the entire lineup of 18 models, shown in late 1981: the negative offset front suspension, previously available only on the Turbo and Diesel models, was made standard. The front indicator lenses were changed from orange to clear, bumpers and door handles were