It will get about 4 mpg. DOUBLE what I get in my Dart with a 4150. The old cars were great because they were topped off daily with cheap primo before going home from work. The gas stations were always full of bull, especially when you drove in to the isle, driving a striped, muscle car with high impact paint. At night, under the lights, was even cooler. Stopping for a cold beverage wasn't unheard of. So my take on this is that if you are going to daily drive an old car, with any "performance" mods at all, get ready to pay the piper. Even the newer, high powered cars burn GAS! Big time! You might get 20 idling down the road in overdrive in a new Corvette. Only because I think it would be the lightest of the bunch. I know nothing about foreign cars and their engines.