How do modern cars regulate temperature so well?

25 degree (or more) temperature swings?
Mine's always been that way. I mean, it's no where near overheating. If it gets to 215° or so, I'd start to be concerned. Assuming you are using 50/50 antifreeze/water, and the stock 14-psi pressure, boilover is way up around around 250° (of course we don't want it running anywhere near that hot!).