I'm a new GXP owner. I've had the car for about two weeks and have put two full tankfuls through. I'm getting very terrible MPG. (about 14 and I'm almost never stepping hard on the gas)

I took it into the dealer on an unrealted issue (the battery went dead) and they said they needed to replace the fuel pressure relay. Do you think that was the source of the bad MPG or do I need to look at something else?

Thank you!