Outdoor Girl wrote:
"According to my vehicle's computer, idling uses far more gas than actually driving. It is also more polluting because it doesn't burn the gas fully. It can be very hard on the engine and not recommended. My vehicle also has synthetic oil and it is recommended to only let it idle for a few seconds, even when it is cold."
I'm guessing that this comes from the computer trying to calculate gas mileage from a non-moving car and that will make it report poor efficiency because idling means fuel burned for no movement. However, an engine at idle will burn a lot less fuel in a given time than an engine in a moving car. It is more polluting specifically due to the reason you mentioned, but as to it being hard on the engine in most cases it's really not. There are situations where it can cause problems if you idle for excessive periods for many years (like a taxicab or police cruiser) but for most people they just don't idle a car long enough to cause any sort of problem other than fuel waste and increased emissions. The recommendation on synthetic oil isn't meant to be a warning so much as an assurance that it's not necessary to idle the engine as long to get it to optimum viscosity, unlike natural motor oil that can lose viscosity (and therefore the ability to protect engine parts) more readily in cold conditions.
"If I get stuck in traffic and it is obvious that it is going to be a while before I move, like when I get stuck at a train crossing, I'll actually turn the car off."
That's still a good idea just because of the fuel waste issue. Gasoline ain't cheap.