[MetroMPG]

Welcome.

So your main goal is your wife's vehicle... is she on board with this money saving business?? Sounds like she might not be, given the vehicle choice.

If she is on board, first goal (assuming immediately trading for a more cost efficient vehicle isn't an option!) should be adjusting the nut behind the wheel. She needs instant feedback to start tracking her results (playing the "beat the high score" game). That means a resettable average & instant MPG gauge.

If she isn't on board, good luck! (What's that saying about horses & water?)