Test-driving a used car is double the trouble and double the fun of taking that brand new set of wheels off the showroom floor — but this 18-point checklist will help.

If you’re going to take the gamble by buying a used car, you should do it right, and that means two test-drives instead of one. Yeah, it’s a little more time consuming, but it affords you the opportunity to evaluate not just the quality of the drive and the ride, but also the vehicle’s mechanical wellness.

The first test-drive will be for your personal evaluation. But it’s also your chance to jot down the Vehicle Identification Number, or VIN, so you can later run a vehicle history report at Carfax.com or AutoCheck.com.

The second test-run — assuming the history looks OK and you like the car — will be to take the car to a trusted mechanic for a second opinion.

At the starting line

Before you even climb behind the wheel for that initial evaluation, however, here are 12 important things to look for — in daylight:

1. Examine the tires individually. Does each have at least a quarter of an inch of tread? Is the wear even? Are the tires matched in size and brand?

2. If the vehicle has wheels with spokes, look through the openings on the front wheels to check the disc brake rotors. Are they scored?

3. Look under the car for fluid leaks. Do this with the engine off and again with it running.

4. Squat at the front corners of the car and look down along its sides for ripples that might indicate body repairs.

5. Open and close all the doors and the trunk. Make sure all operate smoothly.

6. Lock and unlock all the doors from inside and out.

7. Ask the salesman or owner to sit behind the wheel and operate the headlights, brake lights and turn signals as you verify that they work.

8. Open the hood with the engine running and listen for knocks, ticks or hisses.

9. Check door edges and hinges for rust.

10. Lift up the pad or carpet in the trunk and check for rust.

11. Slide behind the steering wheel and make sure the controls for every system operate properly. Does the air conditioner cool, does the heater heat, does the CD player work?

12. If there is an air freshener hanging from the rearview mirror or the interior smells as though it was just sprayed with air freshener, open the doors for a few minutes and let it air out. By the time your test-drive is completed, the air freshener smell should be gone and you can get a better idea of the odors you will have to live with.

As you drive

As with test-driving a new car, you still need to focus on how the vehicle accelerates, brakes, rides, corners, parks and steers. But with a used car, you also must listen for persistent sounds and feel for odd vibrations that may be harbingers of costly future repairs. These should be brought to the attention of your mechanic if you decide to continue on to the second test-drive.

Add these six points to your checklist:

1. Make sure you drive the vehicle above 60 miles per hour at some point. Many front-end problems aren’t detectible at lower speeds. Does the front end shake, shimmy or vibrate?

2. Does the steering wheel vibrate at any speed?

3. Are there any odd noises when you accelerate from a standstill?

4. Does the vehicle pull to one side or the other when you accelerate? Find a large, empty parking lot. At 20 miles per hour or so, let go of the steering wheel; does the vehicle pull to one side or the other?

5. Does the transmission shift smoothly?

6. Apply the brakes; does the pedal feel squishy? Does the vehicle pull to one side or the other when braking?

It’s been said that buying a used car is buying someone else’s problems. You can minimize the odds of that happening by spending a little extra time and taking a few extra precautions.

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