"Your car engine can typically deliver 150 horse power to the wheels, but after 6 seconds of that you are at freeway speeds and then your engine is only deliver

"Your car engine can typically deliver 150 horse power to the wheels, but after 6 seconds of that you are at freeway speeds and then your engine is only delivering about 25 horsepower." Unless you're in Colorado doing 80 mph, uphill for ten miles, fully loaded with cargo - then you engine brake (ie dissipate your KE into the engine block) on the way down. Or you take you car to the track. In both situations your cooling system is still expected to deliver, and does, since its not that big an issue to size it properly and a massive reliability issue if it isn't.