I'm not sure how to ask this, but I've noticed that when I let out the pressure by opening the gas cap before driving I don't use so much gas. If I don't, especially when it's a hot day, I use more gas and the car feel like it's running sluggish. I also smell gas from exhaust. Can someone explain this if it makes any sense?

Leo
99RS (AT)

yeah well all cars run more sluggish on hot days than cold days and as for the gas tank pressure hypothesis, there is nothing related to fuel consumption/fuel pressure with the pressure in your tank...your fuel pump is at a constant fuel pressure reguardless of any tank pressure.