Willie via EV wrote:
On 5/18/19 12:38 PM, Haudy Kazemi via EV wrote:

drag and increased energy consumption (and reduced range). Simply
raising a
vehicle increases frontal area by virtue of the tires being more exposed.

I believe the under car air speed is also increased.  Or, maybe
increased turbulence.  Anyway, I think it is worse than just exposing
more tire.

I think that is true. Keeping the car low is a way to reduce the amount of air and turbulence underneath. Of course, a smooth bottom would help; but that costs too much.

Big fat tires with lots of tread have lots of wind resistance. And, the tops of the tires are moving forward at *double* the speed of the car!

Paul MacReady (of Aerovironment) talked a lot about auto aerodynamics when he was designing the Impact (aka GM EV1). Things I recall:

- Aero testing is in wind tunnels, with car and tires not moving.
- The roughness of the bottom of the car is usually ignored.
- Spinning tires have much more drag than stationary ones.
- Most cars are more aerodynamic in reverse.

So, he designed the EV1 with a smooth bottom, with wheel wells optimized as "ducts" to minimize turbulence, and a shape that actually *was* aerodynamic (instead of what some stylist thinks will "look" aerodynamic).

If you need more ground clearance sometimes, maybe adjustable air bags are an answer?
--
Fools ignore complexity. Pragmatists suffer it. The wise avoid it.
Geniuses remove it. -- Alan Perlis, "Epigrams on Programming"
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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