Oldsmobile W-31
Since the muscle car segment exploded in 1970 with big block power, some manufacturers offered smaller and nimbler alternatives to 427, 455, or 454 engines. One of those forgotten and obscure models is Oldsmobile W31 (via Hemmings).

You all know about Olds Rally 350 model made for 1970 only, but this W31 was its twin car with less “in your face” styling and similar power from a high-revving 350 V8. The vehicle featured many “go fast” options, but it flew under the radar since most customers didn’t know it existed. In the end, Oldsmobile produced just 116 of those interesting machines for the 1970 model year.