depending on the aeromods and gearing i think you could wring 40MPG out of a 914 with a ej25, turbo it and set up a few different fuel maps like you mentioned and you could have a really fun DD. but like we've said, no back seat.
On the 40 MPG note, i got 41.5 MPG over a 135 mile stretch in my girlfriends Focus(with an auto), and that was with 4 people in the car along with luggage for the weekend, and all i had done to it was a front belly pan.
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