My new '74 Z28 sure wasn't fast. IIRC, it was rated at 240 hp. I don't think that it would even break the rear tires loose. On top of that it would get 12 mpg, driving at 60 mph on the highway. I once drove it 90 miles around my small home town and burned up 15 gallons - that's 6 mpg. I sold it quickly and got a new '75 El Camino with a 350 2-barrel that I believe was rated at 170 hp. It would get 15 mpg, city or highway.

Compare that to my 2014 Corvette. 455 hp and it gets 20 mpg around town. It's rated for a lot better mileage on the highway.