I drew my dream eco/sports car a while ago, here is the picture I would be basing this car off of.
Here would be the realistic donor car, a 1991-1997 Mazda MX-6
Budget Bracket {$0-->$5000,$5001-->$15,000,$15001-->$30,000,$30,000+}
$15,000-$30,000
Purpose of car {Daily driver around town, Daily Driver longer distance, 1/2 ton Work Truck (or Van), 1 ton work truck (Or van), luxury touring, sports car}
Sports car
Proposed basis for car {Ground up build from raw materials, Kit car, previous production car}
The closest reasonable car I can find to my drawn design would be the 1991-1997 Mazda MX-6
Engine of choice
One of two inline sixes: Either a 1JZ (2.5) or a 2JZ (3.0)
Transmission of choice
A 6+ speed manual compatible with a mid engine RWD layout.
Drivetrain of choice {fwd, rwd, 4wd, other}
Rear wheel drive
Modifications required to above
The base car would require extensive modifications to turn it into what I would want it to be. Most notably would be the switch from front engine front wheel drive to mid engine rear wheel drive. Another big switch would be the changes to the cooling system. My design features a cooling system which would utilize the meredith effect to minimize drag from the cooling system.
Expected mileage
As far as EPA ratings, maybe 21 city, 32 highway? Ideally, it should be able to achieve 50 MPG highway with my driving style.
Expected cost to build
Probably in the $15K-$30K range. Custom fabrication would probably have to be farmed out to turn a 1-2JZ into a mid engine rear wheel drive.