North America was the key market for this Personal luxury car, and two thirds of R107 and C107 production was sold there. The R107/C107 for the North American market sported four round low-output sealed beam headlights, due to unique U.S. regulations. Sales in North America began in 1972, and cars wore the badge 350 SL, but actually had a larger 4.5L V8 with 3 speed auto (and were renamed 450 SL for model year 1973); the big V8 became available on other markets with the official introduction of the 450 SL/SLC on non-North American markets in March 1973. US cars sold from 1972 through 1975 used the Bosch D Jetronic fuel injection system, an early electronic engine management system. From 1974, the front and rear bumpers were dramatically lengthened, by 8 inches (203 mm) on each end, to comply with the U.S. National Highway Traffic Safety Administration regulations, that mandated no damage at an impact of 5-mile-per-hour (8 km/h). R107 and C107 cars were exported to the US with low compression 4.5 liter V8 engines to meet stringent US emissions requirements, yet still provide adequate power. US models sold from 1976 through 1979 used the Bosch K Jetronic system, an entirely mechanical fuel injection system. The 450 SL was produced until 1980. Starting in 1980, US cars were equipped with lambda control, which varied the air/fuel mixture based on feedback from an oxygen sensor. The smaller engined 380 SL replaced the 450SL from 1981 to 1985. The Malaise era 380 SL was the least powerful of the US market R107 roadsters. North American market SL and SLC models retained the "protruding" 5 mph bumpers, even after the wisdom of the law was reconsidered in 1981.