Dear Tom and Ray:

I just read your article on parking and realized I don't know how to park my car. I read somewhere else that parking in Second or Third gear (with a manual transmission) is the best. I remember the rationale being that First and Reverse are pretty important, and if someone were to hit your car while parked and a tooth in Second or Third gear became chipped, you could still drive the car. Should I keep parking in Second, or do I go with your advice? -- Chris

TOM: Well, we hate to recommend our own advice, but unfortunately, we've backed ourselves into a corner today because we're absolutely right.

RAY: You most certainly DO want to leave the transmission in First or Reverse when you park a car with a stick shift.

TOM: The idea behind putting it in gear is that you want to connect the wheels to the engine and use the compression of the engine to help prevent the car from moving. If the wheels have to make the cylinders compress their air in order to go anywhere, the car will have a harder time rolling away.

RAY: And you want to use the gear with the highest ratio, because then the wheels have to turn more times to make the engine turn once. And First gear or Reverse always have the highest ratios (they're actually very close, so, practically speaking, you can use either one).

TOM: But even if you're in First or Reverse, don't count on the engine compression to keep the car from moving. There are lots of things that can go wrong.

RAY: The hill you're parked on could be steep enough to overcome the compression of the engine. Or if you have a tiny little engine -- or an old, worn-out engine -- you might not have enough compression to hold off two or three thousand pounds of downhill-pointing car. And once a car starts rolling, inertia takes over, and you're done for.

TOM: Or if you have a bad clutch, the wheels won't really be connected to the engine at all -- even if you leave it in gear.

RAY: So no matter what gear you leave your car in, you should always use the parking brake, too. Parking brakes are rather flimsy things that can't be relied on either. That's why automakers' lawyers made them change the name from "emergency brake" to "parking brake." But between the two -- using the parking brake and putting the car in First or Reverse (and turning the wheels toward the curb if you're on a hill) -- and barring criminal activity or a teen-ager in the house, the car ought to be there when you come back, Chris.