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Automatic transmissions: coasting and parking

I just got a car that has an automatic transmission and am getting used to driving an auto. Does it do damage to coast in neutral and put it in drive while moving at any speed? When parking, will putting the transmission in P work or do you need to put the parking brake on also?

It won’t do harm, but it doesn’t help anything either. You should not do it. Neutral is only really there to use if the car has to be towed or pushed.
You should always use the parking brake when you park the car. Apply the parking brake before you release the foot brake. This will keep you transmission from getting stuck in park, keep the parking brake in working condition, and keep your car from rolling away should the transmission fail.

It is not a good idea to put it in neutral while driving and in some states it would be illegal.  It is a little less safe.  It is not likely to damage a modern transmission, but they why do it anyway? 

When parking ALWASY set the parking brake first.

I agree with the above posts on not using neutral and using the parking brake. However, I admit to ignoring the last bit of good advice routinely, and have not had a problem in flat Dallas. If you live in a hilly area, definitely use the parking brake, but I have a question for folks - how often have they experienced a problem resulting from failure to use the parking brake with an AT?

There is no reason to shift an automatic to neutral while the car is in motion. Doing so actually uses MORE fuel than keeping the transmission in gear, and can be a significant safety hazard.

The car’s computer shuts off the fuel injectors when you take your foot off the accelerator, so the engine uses no gas. If you shift to neutral, however, the computer keeps the fuel injectors pulsing with enough fuel to maintain idle speed (but not vehicle speed).

Leave it in gear and save both fuel and wear-and-tear.

ALWAYS use the parking brake when parking the car, regardless of the transmission type. That’s what it’s for. The transmission is designed to make the car go. The parking brake is designed to keep the vehicle in place when it’s parked.

You just got a car with a auto trans and you are already starting bad habits, what kind of habits did you have with your manual trans car? where you coasting in neutral in it?

Yeah, I’ve been coasting since 1982. Hard to do in an auto.

A thought if you live in a hilly area and have an older car whose parking brake you may not trust not to freeze for extended periods; use curbs and carry something to block the wheel. If you’re lucky enough to live in “rock” country, they are ready made. i have them strategically placed around my property for that purpose and carry them (wedges from tree under cuts) in my older vehicles. A little added piece of mind. Be sure to roll into it BEFORE you place it into park.