What's Wrong With Coasting?

Dear Car Talk

Dear Car Talk | Nov 25, 2014

Dear Car Talk:

My husband and I have a real bone to pick with you after an answer you gave on the radio a couple of weeks ago. A woman called in saying a guy-friend of hers insisted that when slowing to a stop, she should shift down through each gear, from fifth to first, as she stops. She said that she never does that. Instead, she puts the car in neutral right away and lets it roll to a stop. You said they were both wrong! You said the guy-friend was wrong because the clutch would wear out faster, and it costs more to fix than the brakes. You said she was wrong, too, but you didn't say why! This is driving us nuts! Why is it wrong to put the car in neutral and coast when you see a stop up ahead? We're losing sleep over this. Thanks!

-- Lee

Oh, so you're the one who's been calling my house in the middle of the night for the past six weeks! You are right that we've never recommended shifting down through all of the gears when coming to a stop. That's excessive (though it is fun). While it does save some wear on the brakes, it uses up a lot of your clutch disc over time. And as Ricky Ricardo would say: Clutches are 'spensive, Lucy!

On the other hand, if you just pop the transmission into neutral, you give up all the natural engine braking. And you lose the ability to accelerate suddenly in an emergency if you need to. Granted, these are minor arguments, Lee. No one's going to haul you to the International Court of Justice at The Hague for coasting to a stop in neutral.

But this is how I do it: If I'm driving along at 40 mph in fourth gear and see a red light up ahead, I just let up on the gas and use the brake as needed, leaving the car in gear. That way, I get some help with slowing the car from the natural engine braking (which takes advantage of compression, and does no harm to the engine). And if someone swerved at me or was suddenly heading at me from the other direction and I needed to get out of the way quickly, I'd be able to accelerate without having to first fumble for the shifter. Then, when I get down to 10 or 15 mph, I push in the clutch and put the car in neutral and brake to a stop. Now, you may ask: Is that scenario -- where you suddenly need to accelerate again -- a likely one? No. Has it ever happened to me? No. So you're not committing a crime against car-manity by coasting in neutral. But if I were teaching a new driver, that's the way I would do it -- to maximize control over the car. Hope you can get back to sleep now, Lee.


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