I agree with the guys above. Everything about getting good MPG points to the Metro. It's a smaller, more efficient platform to start with, then you've got the more efficient transmission, and it allows you to do EOC if you're comfortable with that.
Trading down from an Expedition, you will see a tremendous improvement either way, but the potential is there to reduce your fuel consumption probably 30-40% again in the Metro vs. the Civic. I see delivery guys in my city getting 30 MPG city in auto Civics frequently, but the Metro should be able to see at least 40 MPG pretty consistently if you keep it in good shape and drive it efficiently.
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