My son, Sean, is now driving the 1992 BMW 525i. He has replaced all the door panels that were delaminating, had the headliner re-upolstered, and put custom led taillights in the car. It is finally inspected and on the road. Today, he pulled out of our development and headed towards a major highway. He noticed a middle age guy behind him who was tailing him and gesturing to pull over. The guy pulled up to him and said that he saw "flames" coming out of the tail pipe!

Now, I have seen flames coming out of exhaust headers of race cars but from the exhaust manifold to the tail pipe is probably a good ten feet. The only thing my son has done recently is to run premium gas instead of regular in the car. The exhaust system is new from the catalytic converter back to the tail pipe.

My son said the guy was serious. Was the middle age guy smoking something, seeing things, or is it really possible that something like this could happen. If so, what are the causes and how do you go about correcting the problem. Help, Winfred!