My memory ain't great, but I recall Vettes being 7 seconds around 1970.

I just don't see a turbo 4 back then doing what Volvo claims here. Maybe 1975, compared to a "malaise years" V8 because of lowered compression from emissions requirements.

1980's turbo, possibly, but only once as the whole thing overheated. Had a turbo in the 80's,and it was not blowing away v8's - it was keeping up. Though it handled way better.

By 1990? Definitely.