Hello everyone, I am wondering if there is any reason why letting a car engine idle for extended periods of time would inherently be bad for it. I know that whenever the engine is running everything is inherently wearing out and with all else being equal the more hours on it the more frequently it will require maintenance, but is there anything worse about idling all day than, say, driving down the highway all day? For the purpose of this question let's assume that the vehicle in question has a well maintained and correctly functioning modern fuel injected engine, a good cooling system that keeps the engine's temp in a normal range at all times, and no significant design flaws.