I have a 2008 G6 that I purchased in Oct of 2008 it had 13,048 miles on it when I bought it.
I am having a HUGE mileage issue with it, I am getting about 11MPG in the city. I never really kept track of what I was spending in Gas until recently.
I was filling up at about 1/2 tanks and getting about 93 miles. So when i questioned the dealer about it they basically said that it was not possible that the car was getting that kind of mileage and they wanted me to fill it, Mark down my mileage and then drive it til empty go back to the same gas station & same gas pump and then figure out the miles used and figure it out manually. (Which is what I was doing anyway) But I was not letting it go to empty. I do not understand what the differance is if I fill at half tanks or full tanks as it is Miles driven to gal used.... SO to humor myself I filled the car drove it until 1/4 tank of gas and hmm... got the same about 11 MPG in the city.
When I returned to the dealer, They basically said again that it is not possible to get that mileage and not have a check engine light on, or to have a black tail pipe. They did book the car in and said that they checked the converter, ect. They said that they called GM and that there are no known issues. I was asked again to pick the car up and drive it until the gas LIGHT COMES ON and then go back to the same station and refill the car. I am not sure how doing this is going to make any differance. I took the car back and I am still on that tank of gas, I am at about 111 miles and have burned approx 3/4 tank of gas. so it will not be long before my gas light is on I'm sure
I do not drive my car hard, nor do I put alot of miles on it but they are all city, Nor do I idle for long periods of time besides being in a drive thru ect. I have owned the car for 2 years and have put about 4970 Miles on it.
They did call me yesterday and said that they have no idea and are at a loss at the moment. I told them that I have NO PROBLEM dropping the car off for them to take and have someone drive it for a tank of gas and they could see for themselves. He said well it may have to come down to that.
ANYONE HAVE ANY INFO OR IDEAS ON WHAT COULD CAUSE THIS?
Any Info would be greatly appreciated...