What would cause my L67 3800 to have a cloud of exhaust fume even when it is 80 degrees out? Could this be where the majority of my gas mileage is going?
2002 Bonneville SSEi series II L67. There seems to be a lot of carbon residue building around my exhaust on the bumper. Right now, with the foot out of the pedal it is only getting 21.5 mpg.