A three-wheel car is, by design, basically a triangle shape. Depending on where the passengers sit, the location of the engine, and the placement of other critical mechanical components, this means the car either has two wheels up front and one in the rear or two wheels in the rear and one up front. The engine can drive the single rear wheel or the two rear wheels, and the steering can be done either way as well.
Having one wheel up front and two in the back is known as the delta configuration. Karl Benz's creation followed this setup, as did the Reliant Robin. The original three-wheeled Mazda automobile, the Mazda-Go, was configured this way to allow for a pickup truck bed in the back.
The benefit to the delta setup is its inherent low cost. Most cars set up this way have the engine driving the rear wheels and leave steering to the front one. It's relatively easy (and inexpensive) to build a steering setup with only one wheel.
The second type of three-wheeler setup is called the tadpole or reverse trike. The opposite of the delta, this formation has two wheels up front and one in the back. This setup is the basis for the speedy Campagna Motors T-Rex, as well as the exciting Volkswagen GX-3 concept vehicle.
Tadpole designs are much more stable than the delta setup because the back wheel drives the vehicle while the two wheels up front are responsible for steering. There's also an aerodynamic benefit, since the vehicle is shaped almost like a teardrop -- wide and round up front and tapering off in the rear. This allows air to flow easily over the vehicle's bodywork.
The tadpole design is becoming more and more favored among auto designers for its stability, aerodynamics and ability to house a fuel-efficient engine. In fact, a number of current hybrid and electric concept vehicles use a three-wheel setup along these lines. As cars get more eco-friendly, you may be seeing more and more three-wheelers on the road than ever before.
On the next page, we'll examine the advantages behind having a car with fewer than four wheels.