I've had low MPG in this car and I've attributed it to running around mountainsides and using the AC more than usual. But I've dropped to the city MPG to around 37 which is 10 MPG less than normal. I do have a check engine light on but the dealer said it was an aftermarket add to the car so they wouldn't look at it. They saw the car 4 months ago, but I don't want to bring it back because they will continue to say it isn't them. I'm not sure where to turn. The aftermarket item said it is fully tested and guaranteed not to affect warranty and they gave a sticker to add to the vehicle so they can see the code of approval.