Have a 1980 450SL, (last year), bought new. My Dad also bought a '76 new and kept it for 4 years. Those were the days when MB was the best car in the world, build quality-wise, hands down. The technology is ancient, (late '60s/early '70s development), but they are decent driving cars. Terrible gas mileage but fuel is cheap at the moment. Our 1980 calls for 87 octane in the owners manual. (8.5:1 CR).
Here it was last fall:
