How can you be sure the mileage on that used car you're thinking about is accurate? How do you know it hasn't been rolled back?

Not every used-car dealer, or everybody who runs an ad in the paper, is cheating; but there are enough unethical used-car sellers around - private as well as dealers - that it pays to beware. Knowing what to look for when you're shopping can help you tell if the odometer is accurate.

Check the body. Not just the sides, front and back - underneath, too. Rust lowers the value of a car and, if it's really bad, may require expensive bodywork.

Is the paint all the same shade? One area that's a different shade may indicate that the car has been wrecked and then repaired.

The same with seams around doors, hood and trunk lid: Are they all about the same width? Or did an accident bend the body?

If possible, follow the car down the road while it's driven, and watch to see if the front wheels line up with the back. If the car looks like a dog running down the street, with the rear wheels a little to the left or right of the front wheels, you don't want that car. By the same token, do the doors open and close easily, or sag?

Inside, where you and your passengers will spend your time, look at the upholstery, especially where the driver sits. How worn is it? If the odometer shows only 20,000 miles, but the driver's seat is severly worn, think twice. How about arm-rests, especially the driver's? Or the pedals? Also compare evenness of wear. For example, if the arm-rest is heavily worn, and the pedals aren't worn at all, new pedals may have been put on to make things look better. Look at the carpets and headliner also, since inexpensive fluids readily available can shine the pedals and floor-mats up.

Check all door handles and locks. If any are missing or broken, that's another expense after you buy the car.

Make sure the headlights, parking lights, taillights, brake lights, turn signals, dash lights and interior light all work.

Sit in all the seats to make sure there are no broken springs or other problems. Roll all the windows up an down - any that don't work properly will have to be fixed.

Open the trunk and look for moisture and rust. Dampness may indicate a leak. Do you want to put your new luggage in there?

Open the hood. How does the engine look? If it's spotless and the car has more than a few thousand miles on it, the engine has probably been cleaned, a possible cause for suspicion. Engines naturally collect a certain amount of dirt. A car with 20,000 miles on it will not have a spotless engine.

On the other hand, the engine should not show signs of leaking gas around the carburetor or intake manifold, or oil from around the value covers or the oil pan (yes, look underneath), or transmission fluid from the transmission, or fluid from the rear end - no matter what its mileage. Don't confuse seepage and leakage: A little seepage may be acceptable, but out-and-out wetness is not.

Pay particular attention to the engine dipstick and the transmission fluid dipstick. Heavy sludge and grit on the engine dipstick is not good; give the car a pass. Neither is black jelly-like fluid on the automatic transmission dipstick - a transmission rebuild may be just around the corner.

Drive the car. Does it handle well? If it bounces and sways around corners or over bumps, the shocks may be bad. Hit the brakes fairly hard when it's safe. Does the car pull to one side? You don't want that, either - that will have to fixed.

Check the tires. Worn tires, especially if they're of the expensive high-mileage variety on a supposedly low-mileage vehicle, may tell badly, they'll need replacement.

In general, if you make all these checks, and everything comes out okay, the car is probably a good buy - if the price is reasonable, of course - regardless of the mileage indicated on the odometer.

But if the car doesn't measure up in a lot of places and the odometer reads a low mileage figure - look at another car.