avoiding engine idle

[oj88]

Heat soak happens when your engine is on inside a stationary car, with no moving air coming in the front except from the fans (which sometimes isn't enough). Turning off the engine then turning the key back to the "on" position turns the fans back on... which cools the engine bay a bit.

Yes, there is the problem of extra wear and tear on the starter... but a hot engine is much, much easier to start than a cold one, so it's not that bad.

Newer cars with start-stop functions to save fuel, though, have higher-speed starters to minimize wear.

An idle car has its coolant circulating and the fans blowing off the hot air from the radiator so there's little or no heat soak there (tubro intercoolers are another thing). Once you turn off the engine, the coolant stops and the residual heat on the engine block creates hot spots. On some engines, you'll hear hissing (other than the catalytic converter) of boiling coolant. Though, this happens anyway after a reasonably long drive, but what you want to achieve is to minimize this type of extreme heat cycling.

As with cars with start-stop functions, is this the hybrid? If it is, I think they don't have starters anymore. The electric motor directly coupled to the crank shaft does that. The motor is used for starting the gas engine, electric propulsion, and for charging the batteries. And since it is directly coupled, there are no gears or solenoids to wear down like those found on conventional starters.

Hybrids also have an electric water pump to circulate coolant even with the gas engine turned off. This helps prevents heatsoak, as well as providing heated air to passengers even with the engine off.