I'm getting very poor gas mileage. (8.9 city/12 highway) I've taken my vehicle to the dealership 4 times and first they said they would do an oil consumption test. That was completed and they replaced my piston rings. I'm spending so much money on fuel, it's ridiculous. I asked for a tune-up and they said GMC doesn't recommend a tune up until 100,000 miles.
My car has 69897 miles.
My car has an automatic transmission.
Hello. If they replaced your piston rings and the problem has persisted, then it is likely that the problem was not related to the piston rings. Most fuel issues are related to engine performance or fuel system problems. A tune up would not be a bad idea, but I would recommend having the fuel and engine management systems thoroughly diagnosed as the MPG that you are experiencing is way below the acceptable rating for that vehicle.
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