Q. What will automakers do if crude oil -- and thus gas prices -- keep falling? Domestic auto companies seem to be working hard to develop smaller, more fuel-efficient cars. But will lots of people return to larger, heavier, less-economical and more profitable vehicles if gas drops to, say, $3 a gallon? --J.J., Barrington

A. U.S. automakers are developing far more attractive smaller vehicles than past models, equipping them so they're more profitable than their old bare-bones small economy cars -- for which few comfort and convenience items were offered. And, although prices for crude oil are falling as of this writing, it's doubtful after a fairly long, painful period of $4-a-gallon gas that we'll see a major move back to large SUVs or pickup trucks by folks who bought such vehicles because it was trendy to own them. Moreover, to save lots of money developing all-new models, U.S. automakers are learning how to adapt their successful European small models to the U.S. market. Some also are jointly developing attractive smaller cars with foreign automakers. Still, higher truck sales generated by those who need a truck for work purposes would be a shot in the arm to automakers. There always will be a market for pickup trucks as both work and personal vehicles, especially in states such as Texas, where the pickup long has been called the "Texas Cadillac."

Q. How do you feel about temporary "mini-spare" tires? I don't think they offer the comfort and security of a full-size spare. --E.S., Chicago

A. I'm no fan of mini-spares, sometimes called "space savers." Automakers heavily use mini-spares because they cut fuel-robbing weight and allow more cargo room. Such spares began becoming popular when automakers "downsized" cars and ended up with less room for traditional spare tires. Also developed have been run-flat tires, which let you keep driving to a tire repair location even when flat, but they're mostly for high-performance cars with big, wide tires that wouldn't run very safely with typical mini-spares. Some automakers are replacing any kind of spare tire with Extended Mobility Devices (EMD) that don't address every flat tire situation. An EMD basically is an air compressor that plugs into the cigarette lighter. The compressor propels a liquid sealant material to seal tire "injuries" up to a quarter inch in the tread area. The theory behind the EMD is that a driver who has a flat can more easily remedy the situation than by jacking up a car, removing the damaged tire and replacing it with the spare. However, the Tire Industry Association (TIA) warns that if the tire has sidewall damage, or if the damage is larger than a standard nail, the EMD "essentially will be useless." Also, it said drivers who use an EMD on a damaged tire might be in for a surprise when trying to get it repaired because a shop might refuse to do the job. "Some sealant materials contain petroleum products that damage the tire, so repair technicians must make sure any trace of the compound is removed before repairing the tire, which might cause additional charges. And many tire dealers might refuse to repair a tire exposed to sealant because the exposure voids the new tire warranty, the TIA says.

Q. Any tips on removing tree sap from a car? I must park in the open during the summer. --S.E., Oak Park

A. Use one of the foreign substance removers sold at auto supply stores. Don't use a regular household stain removal product or one you formulate yourself because it likely will eat into the clear-coat protective covering for the car's paint -- and then leave a stain on the paint.

Car question? Send it to Dan Jedlicka, Chicago Sun-Times, 350 N. Orleans, Chicago 60654, or e-mail djedlicka@ suntimes.com. Include name and hometown.

Dan Jedlicka is leaving the Sun-Times on a full-time basis as of this weekend but will continue to write about the auto world for the newspaper. He also plans on writing online road tests and other auto-related material in the near future. If you sign up for the mailing list at danjedlicka.com, you will be e-mailed when his Web site fully launches.