It had improved handling, acceleration, and refinement than any previous model Z-car. Nissan made various changes and claimed improvements to the Z31 model throughout its entire production. In 1983, Nissan first offered the 300ZX in Japan. It was introduced in the US one year later. All US-market 1984 model Nissan vehicles carried both Datsun and Nissan nameplates. Along with the arrival of their new flagship sports coupe, Nissan launched an aggressive marketing campaign to promote the brand name change from Datsun to Nissan. The 1984 Model can technically be considered the only year of the "Datsun 300ZX". The 1984 300ZX 50th Anniversary Edition was released in celebration of the company's 50th anniversary year. It was based on the standard 300ZX Turbo but was outfitted with every luxury feature available, a unique black interior with "body sonic" leather seats in addition to widened fender flares, requisite badging, rear quarter panel flares, and sixteen-inch (406 mm) wheels (400 mm). For the 1985 model year, Nissan dropped the Datsun name brand for good, but the car dealers were still known as Datsun dealers. Paul Newman raced in the 1985 GT1 Challenge and won. This was Newman's fourth national championship. Minor changes were made to the 300ZX including a water-cooled turbocharger and smoked taillights. The 1986 model saw wider flared wheel wells, as well as body-color bumpers, and the rear quarter panels, were designed specifically to accommodate factory ground effect style side skirts. 1986 turbo models were equipped with an ordinary hood, markedly losing the turbo "scoop" on the driver's side. To keep up with quickly aging aesthetics, another slight redesign happened in 1987, consisting of new rounded, restyled, and longer front and rear bumpers, new headlights, and new taillights. The black trim on turbo models was now charcoal instead of gloss black, and 1987 Turbo models came with special "smoked" turbo-finned wheels. All 1987 model year turbo cars also received an upgraded manual transmission, and larger and more powerful brakes, and turbo cars produced from 4/87 and later came equipped with a clutch-type limited-slip differential. For the 1988 models, there were again a few small changes. The turbocharger was switched from the Garrett T3 turbo to a lower-inertia T25 turbo, and the engine was from 7.8:1 to an 8.3:1 compression ratio to reduce turbocharger spool time and provide an instant boost at any usable RPM. The interior aluminum accents and chrome door handles