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Comment by pg-gadfly | Hacker News Reader

Actually, electric cars can break using entirely their motors while gaining the energy back. They wear their breakpads reaaally slow.

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Same with combustion engines, called "engine breaking effect". More so, if one drives anticipatively instead of driving ternary (100% acceleration, 100% deceleration, or keeping the velocity). By the way: changing the velocity gently reduces tire wear.

You can do this with manual shifting, but none of the automatics that I drove had this feature of engine breaking. Although I sometimes hack it with my current automat by flooring the pedal and releasing it right after it shiftet to lower gear.

I want to know more about why automatics can't do this, but Wikipedia only has an unsourced claim that "gliding vehicles equipped with torque converter-based automatic transmissions [causes] damage due lack of lubrication."

If you release the accelerator, does it decouple the engine from the wheels?

Gliding refers to shutting off the engine with the car moving, which isn't the same thing as engine braking (using the retarding forces of a running engine to slow the car down). Without the engine running there are various pumps that aren't running and fluid movement that isn't taking place anymore, so certain things won't be getting the proper lubrication while the parts are moving.

https://en.wikipedia.org/wiki/Gliding_(vehicle)

https://en.wikipedia.org/wiki/Engine_braking

Automatics can engine brake -- but in response to the person above who couldn't do it -- they typically do not exhibit that behavior in the default drive gear for fuel economy. (although some torque-converter automatics with inclination sensors will automatically engine brake on downhill grades) Most torque-converter automatic transmission also have selectors for holding particular gears to allow the operator to command engine braking behavior.

As the other person mentioned, the quote you are citing means that you shouldn't spin the wheels of an automatic while the engine is not spinning. The input shaft of an automatic transmission typically drives the transmission's lubrication pump. If you spin the output shaft of a transmission of this design without spinning the input shaft, you are rotating the mechanism without lubrication.

I have a Civic with a CVT, and it engine brakes if I'm going downhill and I tap the brakes.

I would guess it's technically possible, but probably not worth the effort.

My CVT has a "sport" button that lets you engage engine braking, but I've never seen it in an automatic (outside of low gear or "fake manual" type options)

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