What gear is best to park in on a hill?

Dear Car Talk

Dear Car Talk | Aug 01, 1997

Dear Tom and Ray:

Besides complaining about my driving, my wife complains about how I park. She
says when I park facing downhill, I should put my gear shift in Reverse. And
when I park facing uphill, I should put the shifter in First gear. She says
that the engine doesn't want to turn backwards. And if my brakes fail while I'm
parked on a hill, the car is less likely to roll away if I park this way. Does
any of this really matter? -- Carl

RAY: Sure it matters, Fred. My brother used to think this stuff didn't matter.
Then one day his parked car rolled down a hill into Tony "The Leg Breaker"
Testosteroni's brand-new Coupe DeVille. And from his hospital bed that summer,
my brother did quite a bit of reading up on parking techniques.

TOM: And here's what I learned. When you have a stick-shift car and you're
parking on a hill, you need several things to keep the car from rolling. You
need an engine with good compression, a clutch that doesn't slip, a parking
brake that works, and you need to put the shifter in Reverse.

RAY: Why Reverse? So you can make a quick getaway from Tony "The Leg Breaker"
Testosteroni after you smash into his car!

TOM: Actually, Reverse gear generally has the largest gear ratio in the
transmission. That means that the wheels have to turn the greatest number of
times to make the engine turn once. And that's what you want -- you want to
make it as hard as possible for the wheels to turn the engine.

RAY: Is the engine less likely to turn backwards? No. The engine doesn't care
if it's turning backwards or forward. It'll readily turn either way. So you
really want the highest gear ratio, and that's almost always Reverse (and First
is usually very close to that).

TOM: And for extra protection, don't forget to make sure your wheels are turned
in toward the curb when you're parked on a hill, your parking brake is fully
engaged, and you're not parked just upstream from a brand new Cadillac with
"LEGBRKR" plates.

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