hey so i have a 1999 mustang v6. for awhile ever time i get out of my car i smell gas. i thought nothing of it because i had bad spark wires that i just replaced and i thought that was the cause of it. the past few days i have still been smelling it and today as i got out of my car i got something out my truck and i could spell it really bad like as if there was a bucket full in front of me. its not comeing from the gas cap or the muffler it smells on the right side in the back. *if u where behind the car looking at the truck. what could it be? can this also makeing me lose mpg?