Hello,
The mid-Seventies was really bad for the vehicles and pollution control systems. The new regulations went into the effect that really killed lot of power and increased lot of fuel consumption until the manufacturers figured out ways to rectify both.
Some examples: 1975 Chevrolet Nova with six-cylinder and three-speed gearbox got 9mpg in city driving! 1975 Cadillac Eldorado with 8,2-litre V8 motor went from 425 horsepowers (in 1970 edition) to 180 horsepowers.
That doesn't necessarily mean your 450SLC is gas hog. It is more likely that it needs tuning up and pollution control system checked carefully.
My former 1982 Buick Skylark with 2,8-litre V6 motor and automatic gearbox went from 18mpg average to about 5 to 6mpg after "shady-tree" repairs from engine fire. I couldn't figure out the pollution control system so I sold it right after I got it back to running.
Regards, Oliver
Steve wrote: