This part is important too. With the engine running, pop the hood and go check out the engine. Have any leaks appeared that weren't there before? If the seller has something to hide, such as an oil or coolant leak, it might not be hiding anymore after a drive. Don't just look; listen and smell. Is the engine running smoothly? Do you hear any clattering, which could indicate valve problems? Do you smell any bad odors, such as burning oil or the sweet smell of coolant? How about from the exhaust pipe? Is the exhaust fairly clear and colorless, or is it smoky? Is the smoke bluish (a sign of oil being burned) or dramatically white or steamy (possibly a head gasket problem)?
Check under the car again to see if it's leaking. (Note that if you ran the air conditioning, it may leak water, which is normal.)

Who owns the car?

While you have the car in front of you, ask to see the title, and compare the Vehicle Registration Number on the title to the one on the car to be sure they're the same. The Registration Number which is different for every car on the road, is located either at the front bumper of the car or on the rear bumper. You want to be sure the seller really owns the car. If the name on the title differs from the name of the seller, start asking questions.

Call in the inspector

If you're pretty sure you want the car and agree with the seller on a price, stipulate that the sale is contingent upon inspection by a professional mechanic. This should not be a problem for the seller. If it is, he or she probably has something to hide; inspections can't harm the car, and if the seller is uncooperative about making it available for an inspection, perhaps the deal was not meant to be.

An inspection is likely to cost between Rs.250 and Rs.1000. For the higher price, you should expect a compression check, in which the mechanic removes the spark plugs and tests the compression in each cylinder with a meter. Low compression is a reliable indication of age and significant wear. It can be repaired, but it requires the engine to be rebuilt, meaning cars with low compression readings are not worth your time unless you are a mechanic or collector yourself.

Even if you do all the right things and have your perspective car(s) inspected by a pro, something can go wrong right after you buy it — something for which you will have to pay. That's why you owe it to yourself to detect all apparent problems, even if it costs Rs1000 — possibly more than once. Do the math: If a mechanic charges you Rs.750 and rejects three cars you wanted to buy, for sound reasons, you still haven't paid as much as you would for the single average trip to the service station...