Can you coast down hill in Neutral with AT?
 

Or would that destroy the automatic transmission?

.....:popc:.....

You can coast UPHILL in neutral on an automatic if you really wanted, through, whether you make it to the top is another story.

What is it, that makes you ask the question? I mean, there has to be a reason for a question to be asked, right?

Are you flying down a steep hill at the speed of sound or something?

So long as you're going at a reasonable (and safe) speed, you're putting a little less stress on the transmission than you would be, going at the same speed on level ground (or worse, speed going uphill).

And since transmissions aren't blowing up going at highway speeds... well, you do the math.

It's a different story if you force low gear at high speeds... then you can damage the transmission (or the engine). Of course, the other issue is just like the warning in the manual about towing the car. If you turn off the engine while its going downhill, the fluids aren't flowing in the transmission and that is wear/damage the damage comes in.

Sure. But you'll use more fuel in neutral to keep the engine running than in drive; in drive, the motion of the car keeps the engine turning and the fuel injection shuts off gas at more than 1K rpm with no load. That and engine braking helps control the car.

does the fit's AT get oil while in neutral? if yes, then i suppose no issue with cooling.

but wat about engaging drive while in motion? i hear a loud clank sometimes when shifting into D while car is rolling.
id just keep it in D since the injectors shut off anyway.

I think the manual advises towing in neutral for up to 8 hours is ok. Then it needs to be run. I think this is to circulate ATF for lubrication. There should be little heat generated in neutral as it's not churning the torque converter.

Shutting off the engine while coasting in neutral avoids engine braking and uses no fuel. It also turns off the power steering and other essential aux devices (brake booster). I wouldn't go there no matter how OCD you are about hypermiling.

engaging drive from neutral while in motion isn't a problem. I just don't think the savings in engine braking outweigh the fuel used to keep the engine running.

Never ever engage reverse while moving forward (don't ask why I know, and no, it wasn't on a Fit).

Do note that there is a specific priming procedure that needs to be followed first (which is detailed in the manual)—starting the engine, idling with it in various gears in a certain sequence for certain amounts of time, etc. Since this procedure is not equivalent to driving along, it would be a bad idea to shut the engine off while coasting in neutral. (I'm not saying that coasting in neutral in general is a good idea, but it won't harm the transmission.)

Of course, if you have an emergency situation, it's OK to coast or move a short distance in neutral without the engine running—if you run out of gas, say, you needn't worry about coasting onto the shoulder of the road rather than stopping in the travel lane. Likewise, pushing the car onto a trailer or flatbed won't kill the transmission.