wind generator?

[Bicycle Bob]

Whitcomb winglets, seen sticking up on the tips of some airliner wings, recover energy from the wingtip vortex. Theoretically, one can recover some energy from a turbulent wake, but it is easier to prevent it. Those winglets would do just as much good as extra wing area, but are used to save space on the ground.

[Cd]

Way off topic ... kind of out in left field.
I know I am not the first person to see a pickup truck with a fan ( house fan ) in the bed of the truck.
What is funny is to see the fan turning at full speed.

[Ryland]

I think it would be more affective to add streamers to your mirrors, they would add less drag and be easier to install and give less disappointment.

[whokilledthejams]

Originally Posted by Piwoslaw

How about "pop-up windmills", that spring up from your car when you apply the brakes? This turns your momentum into aerodynamic drag and then into electricity, instead of into heat. You would still have traditional brakes for lower speeds.
The cost and weigh of such a setup probably isn't worth it.

Originally Posted by MetroMPG

Regardless of where you place the turbine, the end result will be a net energy loss. There's no free lunch.

The exception would be a turbine which is somehow shielded from the airflow (and where the shield does not negatively affect aerodynamics) but which can pop up into the airflow for the purpose of decelerating. Think: aerodynamic regenerative braking.

Not very efficient, of course (compared to electro mechanical or hydraulic regen).

You know, the Bugatti Veyron has an air brake: when the brakes are applied, the spoiler tilts forward. Last week's Top Gear illustrated this (if you're not in the UK, there are plenty of ways to watch it online).

Still, however, I tend to agree that there would be some cost/weight/complexity/aero penalty no matter what.

Someone who's handy with hydraulic systems could probably make something that piggybacks onto a car's brake line circuit, however.

Failing that, one could conceal a turbine-powered generator inside the car, with Naca ducts as inlets and outlets, with simple flaps that open and close via vacuum or brake lines. There would be minimal aero penalty, and it would be slightly simpler to engineer.

[dichotomous]

ok, how about the ribbon wind generators, throw a couple of them in place of the grill slats, or at least in a high pressure area that will see not a ton of flow. all these take is a little wind to move, and the differentiating pressure instead of windspeed of the grill would get them vibrating nicely I think, with no aero drag induced, possibly even help with that. or throw them along the bottom, specifically after the dirty air of the tires or such, no real drag penalty, but plenty of turbulance to vibrate those nicely.

now combine that with the shock absorber/generators, and you could extend your range really far. they dont really have to provide all that much power, any would help since it would always be there is the car or wind is moving, which, well, at least around here, always is.