i rarely drive my civic maybe 3 times a month tops 7 but the other day i took it out to play and was on the highway when i noticed a lot of smoke comming out the back after i hit about 80mph or 90 then i slowed down and no smoke, and then i stop at a light and take off again and a big ass cloud of smoke came out , and i am wondering what could be the problem or whats happening after that big smoke out the car went back to normal but im concerned on what it did any idea whats up with it .....Please help me out Thanks..........Peace