Inliners International Forums General Discussion Hi Performance 250 build

Yes, I wrote a separate program called the Gasolator for MPG.
It is pretty empirical, based on real MPG data, not EPA nonsense. I think when EPA does their city MPG, they cruise a loop with traffic from 1952, or maybe 1932 or something.

None of our new cars ever get near the EPA city number in REAL city driving, and I do know how to get good MPG.
Similarly, you have to be good AND lucky to equal the EPA highway number. I think they cruise a steady 60mph to get that one.

For a new car, look at the EPA City estimate. That is a good estimate of what your real OVERALL mileage will be. People sit in rush hour parked on the freeway thinking their truck is getting 26mpg. Its really getting less than half that. Log every tankful in your car, it is really revealing.

That said, here is what the Gasolator says about these builds:

250
MPG.....Condition
14.40.....City
16.79.....Overall
19.71.....Highway, 60mph real trip
17.83.....Highway, 70mph real trip

292
MPG.....Condition
13.52.....City
15.73.....Overall
18.42.....Highway, 60mph real trip
16.57.....Highway, 70mph real trip

Just for fun I re-did the 250build with a 200-4r trans, same 3.55 gears, no other changes
250-200.4r
MPG.....Condition
14.34.....City
19.12.....Overall
23.34.....Highway, 60mph real trip
21.45.....Highway, 70mph real trip
No diff in the city but about 3.5mpg better out on the road.
Depends how many freeway trips you plan I guess!