system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why are cars exhaust pipe always located at the rear, not side? And truck exhaust pipe located at the front but high up?
gpt
Side exhaust tend to not do well if a fair number of people burn their clothes and skin getting in and out of the car from the side. Most cars don't have entry ways from the rear. 

Trucks used to (perhaps still do) spend a lot of time running idle (in cold weather, many truckers used to keep their engines running all night even while parked and the driver is sleeping in the cabin). The container or load at the back is detachable and people tend to work there attaching and detaching stuff while the engine continues to run. The high exhaust makes it more comfortable and safe.