Originally Posted by theholycow
You should be able to do much better than 9-11 with your '77 and '86, if not the '63. The '96 should beat all of them easily.
When I had them the other cars got, on average:
96 Grand Marquis: 25 MPG highway 20 city
86 Cadillac: 21 highway 15-18 city depending on traffic
63 impala : 13 in the city, 16 highway. got 20 mpg once going from Lousisana to Florida
This Cougar has never done better than 11 and I think it is due to neglect by previous owners. The engine had an unbelievable amount of sludge, among other things.