French Renault went a bit overboard with the Renault Twizy Z.E. Concept car. The Twizy looks like it has square wheels, this only works in cartoons.
If you look closer though there is a round wheel hidden behind the square shaped front - I think.
The funny looking Twizy is ultra-compact 1+1 zero-emission city car, with 15kW motor (20hp) and footprint barely larger than a scooter (2.3m long, 1.13m wide and turning circle of 3m). It has a top speed of 47mph, with acceleration comparable to 125cc motorbike.
Renault also shows three other electric car concept cars at the IAA 2009. More photos and details on Jalopnik.