Welcome, Steve.

The bottom line is you are not going to get 25mpg or more out of either of those engines. It is a cross between the aerodynamics (or lack thereof) of the vehicle and the design of the engine. We are talking about TBI fuel injection that is at least 17 years old in it's design. It just is not going to happen on a *consistant* basis. Downhill, with a tail wind and the engine off, might net you the low 20's.

If that is your ultimate goal, then buying a small commuter type car is going to be the best route for it.

Good Luck,
Michael