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Old 01-17-2014, 06:33 PM   #7 (permalink)
serialk11r
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Quote:
Originally Posted by basjoos View Post
The lower your cd or the greater your weight, the more easily your car will exceed the posted speed limits on a downhill run unless you use braking to limit the speed. The aerocivic is also a featherweight at 2100 lbs, but with its low cd pushing its terminal velocity somewhere above 100mph, it will easily exceed 75 mph on any reasonable downhill run long enough for it to build up speed. It doesn't even have to be a steep downhill.
Yup, but it's fairly common that a car has 2x the drag of your car. I have around the same drag as a Prius but only 70% the weight. The second steepest long "hill" around here that I've seen is the Bay Bridge, where I top out at 40mph. A Prius would probably top out at 50mph, the speed limit.

Even a Mercedes E class pushing 4000 pounds and with a low Cd would probably have trouble getting to 60mph, but a Lexus LS or Mercedes S class pushing 5000-6000 pounds would probably necessitate engine braking down that moderate downhill, but that's not really the norm.
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