Dear Tom and Ray:

A friend of mine says I am wrong, and I was hoping you would have the answer. Whenever I go on a long trip, I always wash and wax the car before I start, and as the bugs collect, I hit carwashes as needed along the way. Besides, it is great driving a nice, pretty car. My reasoning is that a clean car has less drag, so there is a small improvement in gas mileage. My friend asked me if this was supposed to be a joke. He says the actual difference in gas mileage would be too small to matter. Can you comment? --Steven

RAY: If it makes you feel good to drive a nice, clean car, Steven, then you should absolutely do it. But you're not saving a measurable amount of gas that way -- not unless you're cleaning off some enormous, mutant, three-dimensional bird dropping in the shape of airplane flaps.

TOM: While washing the car won't hurt, you'll certainly spend more on the carwashes than you'll ever save on gasoline. I mean, the special "Gold Service," with underbody wash, the air-drying by six exhaling former Soviet ballerinas, and personalized fuzzy-dice preening has to run you at least $12.95 a pop.

RAY: If you're determined to save gas on a long trip, Steven, your time would be better spent making sure your car has been serviced, your tires are properly inflated, your windows are closed and you drive at the speed limit.