What would cause less fuel mileage? I have a 2012 Canyon with the 3700 Vortec engine. I have noticed that I used to get very good mileage and now it seems that it has gone way down. No engine light has come on, the smell of gas comes in the cab when first started. I have sent it to the dealer and they say that there is nothing wrong with the mileage but I know different. They think the mileage is normal. They can't read with the computer because no light has come on. I used to be able to go up to the cottage and about a quarter of the way back on a tank. The cottage is about 515km (roughly 300m) and the tank is about 66L (roughly 20gal), so about 640kms (roughly 375m) I used to get. Now I only get about about 380kms (roughly 220m) on a tank. Does anyone know what could be causing this? Also what should my rpm's be at when running on the highway anywhere from 100 - 120kms (60 - 80ms)?
There are many things that can effect your mileage. If your smelling fuel on cold starts your coolant temp sensor might be reading lower then the actual outside temp causing the PCM to add more fuel. Its possible for a sensor to be inaccurate but still within the normal range so it wont set a code.