Had a well tuned 80 Aspen 2dr with the stock Holley 1 Barrel and 33,000 orignal miles and best was 18mpg daily commuting to work. Same engine, pulled it and dropped it in my 79 Aspen in my sig pic and installed it with that cars orignal Super Six intake/carb setup with no other changes. Same daily commute and it gets 22 mpg consistently. Oh they both had 2.76 geared 7 1/4" rear ends with automatics. The best I ever got out of it was a 2 and half hour trip one way to Norwalk C.C. last fall and it got 25 mpg.