I've owned a lot of crap so I'll tell ya what I can on them.

The '02 WRX I owned averaged 20-22 city only. 26 straight freeway. Trapped 76mph in the 1/8th mi with $800 in parts... not bad at all. A 2.5L short block is $1300, I know more than you can imagine about those cars. Just ask. They get nasty fast, for cheap. WRXs get the 5 speed, STIs get the 6 speed. All EVOs but the MR have the 5 speed also.

Also had a '98 LS1 Z28 and an '01 LS1 C5. Cam had 3.23:1 gears and the C5 ran 3.15:1s. Both got pretty suprising economy. Vette averaged about 23-25 depending how I drove and the camaro a bit less (19-20) as I drove it a bit crazier.

But with the tall ass gearing and light tire/wheel combo you can lug it on the freeway like that with ease.