Q. I'm interested in buying a classic car to both enjoy driving and for long-term financial gain. But some of the autos I've looked at are really old and I suspect they have rust that's been "covered up" with body filler materials, which eventually deteriorate. How do I protect myself from such a condition? --E.A., Berwyn

A. Except for rare fiberglass body cars, such as the Chevy Corvette, take out a low-strength magnet and see if it sticks to the body. If it doesn't, the car likely has excess body filler.

Q. Henry Ford I was no car enthusiast, but his son, Edsel, who died in the early 1940s, definitely was. What about Henry Ford II, who took over the company in the mid-1940s and helped save it? I hear Henry Ford II was responsible for Ford Motor almost getting into the sports car market years before it built its now highly classic 1955-57 two-seat Thunderbird. --B.H., Chicago

A. Edsel had several sporty cars built for himself in the 1930s without his father's approval. (The old man hated them.) Like Edsel, the young Henry Ford II liked sleek European cars. By the early 1950s, he owned gorgeous Italian Cisitalia 202 and Ferrari 212 Touring Barchetta sports cars. He even asked Ford stylists why they couldn't design a car as beautiful as those autos. Young Henry then arranged to have Cisitalia build several sporty prototype production cars for Ford, financed by Ford Motor and using Ford engines. The effort failed after Cisitalia, in cooperation with Italy's Ghia and Vignale exotic car outfits, built a few prototypes because the Italian firms couldn't adapt to Ford's mass production and parts standardization. When Chevrolet introduced its Corvette sports car in 1953, competitive Ford began work on its successful mass-produced Thunderbird two-seater, designed without outside help.

Q. How much does documentation count when selling an old classic car? My wife laughs at me for saving all the paperwork on my classic, which I'm selling to buy another old car. --S.M., Evanston

A. The laugh's on her. Original documentation can let you get up to 50 percent more in resale value, depending on the classic car. And, if you're looking to buy, it can help you more accurately gauge the value of your investment. These documents can help verify a car's originality, which is extremely important to collectors: Original "build sheet," listing engine serial numbers and such. Copy of title in the original owner's name. Complete maintenance or restoration records. Original warranty documents. Documentation in an official make and model registry of autos such as Shelby Mustangs. Original window sticker (almost priceless). I once sold a totally original 1965 Corvette with its new-car window sticker because I bought it from a fellow Sun-Times employee. His father bought the car new at an Oak Park Chevy dealership that no longer exists and kept the sticker in the glove compartment. Old Corvettes generally have gone though a good number of owners, who have modified them and thus changed their original condition. So the person who bought the 'Vette seemed almost as excited by the Corvette's sticker as he was by the car!

Q. A tree near my driveway drops a syrup-like substance on my new car. How do I get it off without paying a detail shop to do that? --E.M, Berwyn

A. Large auto supply stores carry a wide variety of paint care products that should do the job. But if nothing works, take the car to a detail shop, which sometimes has substance removers known only to professionals. And move that car from the driveway! Even bird droppings are highly acidic and can leave marks on paint that are very difficult to remove.

Q. I enjoyed your article on the Porsche Cayman S (Aug. 9 AutoTimes), but wonder why the car doesn't offer an optional sunroof, when Porsche has always offered some sort of open-air option, such as a sunroof, convertible top or removable Targa roof sections. --G.W., Chicago area

A. Porsche national spokesman Gary Fong says the Cayman's roof isn't long enough to accommodate a slide-open sunroof and that the car's rather extreme roof curvature won't allow one. A sunroof also would cause too much of a headroom loss, said Fong, who noted that Porsche offers a variety of open-air models. Incidentally, the Cayman is based on the Porsche Boxster, which is a convertible.

ATTENTION, READERS: Car question? Send it to Dan Jedlicka, Chicago Sun-Times, 350 N. Orleans, Chicago, IL 60654, or e-mail djedlicka@suntimes.com. Include name, hometown and a self-addressed, stamped envelope to ensure a personal reply.