What kind of damage is done after letting a car idle for 11 hours?

Dear Car Talk | Aug 01, 1992
Dear Tom and Ray:
Cliff
TOM: The car's fine, Cliff. People in New York City leave their cars idling for eleven hours all the time. It's called commuting on the Long Island Expressway!
RAY: Right. There are plenty of vehicles that run all day and all night. Taxicabs are another example.
TOM: And how about the police cars that are always sitting outside the Dunkin Donuts in my neighborhood!
RAY: As long as there was sufficient coolant in the car and the engine didn't overheat, everything's fine.
TOM: And the reason it used so little gas is that it was idling at 700 rpm. When the engine is running that slowly, and it's not being asked to do anything, it doesn't use much gas. In fact, tell your friend he might even consider doing this on purpose during the winter. That way, the car will already be nice and warm when he comes home from work!
Cliff
TOM: The car's fine, Cliff. People in New York City leave their cars idling for eleven hours all the time. It's called commuting on the Long Island Expressway!
RAY: Right. There are plenty of vehicles that run all day and all night. Taxicabs are another example.
TOM: And how about the police cars that are always sitting outside the Dunkin Donuts in my neighborhood!
RAY: As long as there was sufficient coolant in the car and the engine didn't overheat, everything's fine.
TOM: And the reason it used so little gas is that it was idling at 700 rpm. When the engine is running that slowly, and it's not being asked to do anything, it doesn't use much gas. In fact, tell your friend he might even consider doing this on purpose during the winter. That way, the car will already be nice and warm when he comes home from work!
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