Terrible gas mileage - 03 GP GT
My brother'* car. He'* only getting ~15 MPG.
Within the past 1,000 miles we replaced the following:
-- LIM gaskets
-- UIM gaskets
-- Delco wires
-- Delco plugs
-- Delco O2
-- 195 thermostat
-- Coolant flush
-- Air filter
-- Fuel filter
-- Tranny fluid and filter
Car has 123K. His gas mileage was really bad before we did all the work, too. I figured his thermostat was stuck open (or there was a 160 in there). Neither were true. So, we did the plugs, wires, new thrmostat anyway, and an O2. The gas mileage is still really crappy.
He typically lets it warm up 5 minutes or so before driving it. And he doesn't drive it hard (he does mostly highway driving anyway).
Any thoughts? BTW, the cat does not rattle at all.