Are the "low" gears on automatic transmissions ever really useful?

Dear Car Talk

Dear Car Talk | May 01, 2005

Dear Tom and Ray:

You lugheads -- and I mean that in a good way -- keep talking about the proper way to drive a manual transmission. Well, I have an automatic and know nothing about shifting from "Drive" to "1" or "2" and back. Those numbers aren't just for decoration, are they? Thanks for all the laughs. -- Anne

RAY: Actually, they pretty much ARE there for decoration these days, Anne.

TOM: In which case you'd think the car makers would do a better job, wouldn't you? I mean, would a couple of rhinestones or a little glitter kill them?

RAY: Automatic transmissions are pretty much "set it and forget it" these days; 99.9 percent of your forward driving can be done in "Drive." When the transmission needs to be in a lower gear, it'll shift itself into a lower gear.

TOM: There's only one really important exception, and that involves long, steep hills -- but only when you're going down them. On a steep mountain road, where you'd need to be on the brakes pretty much constantly for more than half a mile or so, you should shift the car into a lower gear. Shifting down in that situation uses the inertia of the engine to help keep the car from going too fast.

RAY: That prevents you from overheating your brakes, which leads to brake failure, which leads to a life-insurance claim.

TOM: Try the next lowest gear below "Drive" first. And if you still need to ride the brakes to maintain an appropriate speed, drop down another gear, all the way down to "1" or "Low" if necessary.

RAY: Some people suggest that you downshift for extra power when going up hills, or when your transmission is shifting frequently between two gears. But none of that stuff is really necessary. During normal driving, if the transmission really needs to be in a lower gear, it'll figure this out itself. These are college-educated automatic transmissions we have these days, Anne, so fugetaboudit.

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