I think these discussions are risky because of causation/correlation. Cabs, police cars, UPS/Fed-Ex trucks need engine/transmission rebuilds sooner because the

I think these discussions are risky because of causation/correlation. Cabs, police cars, UPS/Fed-Ex trucks need engine/transmission rebuilds sooner because they stop/start every day all day long. For example a Fed-Ex panel truck with a Cummins engine and Allison drive train will last for about 1 million miles without rebuild if used as a light duty such as a plumber or electrician or personal vehicle. Used as a Fed-Ex delivery vehicle it will need a rebuild at around 410K to 450K miles. Idling is not causing the engine to need a rebuild at 40% of it's normal lifespan, its shutting it off and starting it over and over all day long.