Plan on taking every car you're considering for a good long test drive. You should map out two or three types of road ahead of time to include a highway, normal roads for around-town driving, and a bumpy road that will allow you to slow down and check for creaks and groans. If the owner does not allow you to test-drive the car, then you have a simple solution: Don't buy it!

1. Check the steering.

With the front wheels pointed straight ahead (and the engine on with the car in park for power steering), stick your head out the window and watch the front tire as you slowly turn the steering wheel. The tire should begin to move as you begin to turn the wheel. If the steering wheel has to turn more than two inches before the wheels start moving, the car's steering system could need some expensive repairs.

You can check the power steering when parked by turning the wheel all the way to the left and then all the way to the right. If the car screeches loudly or surges and bounces as you turn the wheel, the car might need a new power steering pump, or it may need repairs to the power steering system.

2. Check the exhaust.

While you drive, check your rear-view mirror and note whether any exhaust smoke is coming from the tail pipe. Blue smoke indicates that the engine may need an expensive overhaul. If it's black, the car may simply need a tune-up or carburetor adjustment. If it's white as you start up but stops after a while, it could be water vapor that had built up in the engine and is nothing to worry about. If the white smoke continues throughout the drive, water from the radiator may be leaking into the engine.

3. Check the brakes.

After the engine warms up, stop the car and push the brake pedal down as far as you can. It should go no more than one and a half inches to the floor. Keep the pedal down for at least a minute. If, during that period, the pedal seems to sink lower, the car could have serious brake problems.

When it's safe to do so during the test drive, step on the brakes hard enough to slow down quickly without skidding. If the car dips forward excessively or pulls to one side, it probably needs brake or suspension work.

4. Check the alignment.

When it's safe to do so, let go of the steering wheel on a level, straight road to see if the car pulls to either side. This pulling could mean something as simple as improper tire pressure or as serious as steering linkage out of alignment. Caution: Be careful in conducting this test, because if the car is severely out of alignment, the wheels could turn sharply.

5. Listen to the engine.

When you're on the highway at cruising speed, listen for unusual sounds of stress and strain. Even if the weather is very cold or very hot, drive with the window rolled all the way down in order to hear any clanks, groans, or other sounds that could signal expensive repairs down the road. As you accelerate, the engine should not feel as if it is laboring. Listen for a pinging or tapping from the engine. This sound may disappear by simply using a higher-octane gas, or it may signal the need for a major engine overhaul. Have your mechanic check it out. Even if you cannot identify the sounds, report anything unusual to the mechanic who inspects the car for you.

6. Listen to the engine idle.

Pull over and let the engine idle while the transmission is in park. It should run smoothly. If you notice any acceleration, hesitation, or uneven performance, the problem could be something as simple as an idle adjustment or as serious as a carburetor overhaul. You shouldn't hear any loud tapping noises coming from the engine. If you do, the car may need expensive valve work. If you hear some light ticking or tapping noises, the car may simply need an adjustment. In either case, be sure to put these noises on your mechanic's checklist.

After you've listened to the engine for a while, turn off the key. The engine should stop immediately; if it continues to run for a few seconds, the car might need a carburetor overhaul, or it may simply require a tune-up.

7. Listen to the transmission.

With your foot on the brake, move the shift lever from drive to reverse several times. If you hear a soft thump or no noise at all, the transmission is operating properly. However, if you hear a loud clank, that's a sign that the car may have a major transmission problem.

In general, the automatic transmission should shift smoothly from gear to gear. Any whining of the transmission, jumping, or irregular performance could indicate big transmission problems down the line. If it seems that the car drops temporarily into neutral while shifting from one gear to the next, your transmission is probably slipping and in need of repair. Don't forget to check the transmission while the car is in reverse. You should drive the car for at least fifty yards in reverse to make sure it runs smoothly and doesn't jump.

If the car has a manual transmission and the engine revs up when you step on the gas with your foot off the clutch and the car in gear, the clutch is slipping. You may have to replace it. If you hear a knocking sound from the transmission, press the clutch in. If the noise disappears, it's probably in the transmission; if it doesn't, there could be problems with the clutch.

Note: Any clanking sounds you hear when you're testing out your transmission could also indicate problems with the universal joint. For example, if you hear a clank each time you go down a hill, the car may have a worn universal joint.

8. Listen for clunks.

Take the car out on a very bumpy road, roll down the windows and drive slowly (five to ten miles per hour) to see if you can hear any unusual clanks or other sounds that may indicate you'll need to have some serious suspension work.

9. Check the heater and air conditioner.

If it's winter, first check the heater by warming up the car. Then check the air-conditioning system. To check the air conditioner, run it through all of its cycles. The air compressor should thump slightly as it kicks on and off. However, if you hear loud banging or rumbling, that's an indication that the air compressor may need replacing. Put your hands over the vents to check the pressure and temperature of the air coming out.

10. Check for inside leaks.

If it's handy on the test drive, try running the car through a car wash. For a few dollars, you'll find out whether the car has any obvious leaks. Otherwise, take the car to a place where you can hose it down vigorously. Directly spray the hose around the windows, vents and trunk.