I'd fit into the category of guys with play cars and efficient daily drivers. Why do i care about economy? Our dependency on foreign oil is scary, and it saves me a ton of money, money that can be spent on better things like taking my girlfriend out to a nice dinner. Also, wrenching for better fuel economy is just as satisfying for me as wrenching for faster trap speeds or a better 60'.... it still involves tinkering.
I have a 1984 Buick Regal T-type thats pretty well modified. Its a turbocharged 3.8L V6. Its street legal but is mainly a track car. I have a FAST B2B computer in the car so i can tune it for economy when cruising. For a car that does 10 second passes with a street tune, it gets a respectable 18mpg city and around 23 highway if i use hypermiling techniques. It has a 200r4 4-spd trans with a non-lockup 3400stall converter. I'm currently redoing the motor with forged steel internals, girdle, and roller cam, and bought a new larger ball bearing turbo. It should be running in the 9's when i'm finished with it. Then i'll probably sell it, because I'm having more fun wrenching for better fuel economy every day and barely drive the buick. Plus, its pretty expensive for a tank of 94-octane pump gas plus a full 2 gallon tank of methanol for the alcohol injection setup i have.
