How do modern cars regulate temperature so well?

Interesting thread. My car acts a lot like Jeff's. (op).

On a 90* day driving around normally, it will stay between 180-190. In bad traffic and lots of red lights it creeps to 205. If it's 75* outside and I'm cruising at 55 mph it runs lower than the thermostat setting of 180.

I don't stress until it starts going over 205.

I wonder if @Ccas can shed some light on the new car cooling.