Zebra is a model found in the source code. Its file name is Zebra.lwo, and its design closely resembles that of Evil Weasel, except by the missing suspension holders and concave wheels. This car isn't present in any of the Re-Volt versions.
There's a concept art in the Gallery of a car with brown stripes. The concept matches with the model's name, so it can be said that Zebra was indeed an unreleased, unfinished or abandoned car.
The model was found in the james_cars folder, and inside it were also ancient mesh and texture files of Evil Weasel (among RC Bandit and R6 Turbo). All those coincidences leads to think that Zebra was the first planned design for Evil Weasel.