Generally, turning off the naturaly aspirated (Non-Turbo Engine directly will never cause any problem and you can do so even if you drive the car for long distances and for more than 5 hours....
but with a TurboCharged Engine you are mostly likely to damage the turbocharger so u ar adviced to let it cool down for atleast 3 to 5 minutes or u can solve the problem by buyin and install the device called TURBO TIMER which wil help keep the an engine runing and turbocharger spining even after u switch of an engine til the running parts are completely cool down
why?
Cars are designed according to high tolerance standards for all weather conditions. Cars are tested in different weather conditions such as the conditions of the Arabian Gulf climate and its high temperatures and also in the cold weather.
So engines bear high temperatures and you should not always cool the engine before turning it off unless there is a problem in the engine.
You may not know:
The temperature of the engine and its parts while deriving for long distances on highways is less than driving on crowded streets.
Why?
Driving on crowded streets leads to increase the temperature of the engine. On the other hand, there are several ways to cool the engine when driving on the highways even if for long distances. The car fan and the 120 speed wind cool down the engine and the whole car as well.