Do you let a car with turbo it idle after a run?

Answer 1

YES! Especially if you have been pushing it hard. Turbo's need to 'cool off' after being used, and is very important if they have been used hard. Oil from the engine will cool the turbo off after a few minutes. Sophisticated cars and cars with twin turbos usually have timers built in to the ignition system which will run the engine for 2-4 minutes after you turn the key off, specifically to cool the turbo(s). You should always idle a car with a turbo before you turn the engine off - longer period of time if it was racing.