Saturn SL2 Engine Poor Mileage

Hello, Got A 2002 Saturn Sl2. Just Changed The Plugs And Wires And Got A Noticeable Increase In Power. Drove Out Of Town This Last...

Great Mpg On The Hwy But About 300% Less In The City, New Plugs, Gas Filter, Air Filter.for Example. 400 -500 Kilometers On The Highway Per...

My Car Is Getting 12 Mpg Both Highway And City Average. I Don't Hot Rod It, And I Warm It Up In The Winter Before I Bring It Out. This...