How do modern cars regulate temperature so well?

so looking into the PWM thing a little more, i (finaly) found a good explination of how it works.

'So, the motor is being fed impulses of power. Imagine it the same way as if you were to turn the wheel with your hand. You can push the wheel every 5 seconds with the same amount of force, and you will keep the wheel spinning. You can also speed up the interval when you are pushing the wheel; let’s say you nudge it every 3 seconds..."

"It is important to know that there is no voltage regulation involved here, and by using PWM regulation the motor is constantly being fed 12 volts."
What is PWM and how does it work? - ekwb.com

SPAL and DERALE both sell them too...