Written Friday November 29, 2013: Updated January 11, 2014
If you have not been following along, I have finished a Geo Metro EV conversion and have applied several previous aeromod enhancements to it.
Regardless of the vehicle, at freeway speeds, if you can improve the aero-dynamics, the fuel efficiency will increase. The beauty of a $350 car is you can do virtually anything and everything without hurting its resale value. What better material to use on a $350 car for aeromods than a $35 sheet of 4x8 plastic from the hardware store. It’s cheap, durable and already matches the paint. It’s high time we put in some more self-taping screws.
The undercarriage aero-mods work great for cleaning up those aero-dynamically dirty areas under the car.
Front covers keep the air steaming seamlessly over the front of the car.
A Kammback is a car body style derived by German scientist Wunibald Kamm in the 1930. It calls for smooth gentle curves with a tail that cuts off abruptly. This in-effect tricks the air into thinking the tail keeps on going.
I wanted to try a Kammback on the Geo EV. My criteria were that it be cheap, not limit driver visibility and not affect the operation of the rear hatch. This is what I came up with.
Rear wheel skirts keep the air flowing past the wheels and out of the wheel wells. Yes, they limit access to the rear tires but then how often do you change tires anyway? For me it’s every 7,500 miles during tire rotations or every 10 months.
Wheel skirts on the front wheels is not as practical since the wheels still need to turn outward.
But I went ahead and added a couple small ones in an attempt to reduce the air getting into the wheel-well.
The Geo Metro has sunken headlights that kind of act like little parachutes for air.
I covered them up with some clear, rigid polycarbonate. I used a heat-gun to crudely mold them to the shape of the car.
Some clear packing tape over all the screws and plastic seams keeps them from contributing additional turbulence and air drag. Surprisingly, tape applied directly to clean metal and plastic holds up to the elements for a really long time. UV light will make it brittle but it takes it a few months. I park in a garage at night so that helps keep the car nicer for longer.
Every car body is different but for a Geo Metro aerodynamic modifications proved out as follows.
Undercarriage cover ~30% reduction in drag
Front covers ~10-15% total
Rear wheel skirts ~2-3%
Front wheel skirts <1 to 1%