Not actually Racing,But Rallying,Mercedes benz themselves rallyed the 450Sl comprehensivly,i remember seeing them in New Zealand.This is the 1980 champion ship winnig version from AMG driven by Clemens Schickendans and Jurg Denselas raced from 1974
and heres part of an Article by jim Mc Graw..
"...not suitable for racing, but they were rallied extensively in the late 1970s, winning the Tour of Britain in 1976, the 18,000-mile Argentine rally, and coming second in the East African Safari Rally with veteran Hannu Mikkola. Another fleet of 450SLC 5.0s finished 1-2-3-4 in the 3,500-mile Bandama rally in December, 1979. These were the first V8, automatic-transmission cars ever to win an FIA rally.
The 450SLC 5.0s were special lightweight 300-bhp 5.0-liter V8 versions of the 450SLC for Group 4, with aluminum engine blocks and reinforced chassis. In 1980, the factory modified them still more, calling it the 500SLC, and ran all season without a win until the last event of the year, the 3,200-mile Ivory Coast rally, which was won by Bjorn Waldegaard in a 450SLC with Jorge Recalde second in one of the new 500SLCs. Their point made, the factory pulled out of rallying a week before Christmas. That generation of SL, the last ever offered with a manual transmission, finished off as the 380SL, 500SL, and the rare 560SL, and lasted until 1989 with continuous upgrades like a four-speed automatic overdrive."