Reference Material for Kart Design of UDK Racing Game

The vehicle design i've tried to keep to a minimal as I don't think my modelling is up to scratch but due to the fact that this unit is in coalition with Digital Modelling, I think extensively pushing my skills is appropriate. For the other AI opponents after colour has been chosen will be designed basically in the same form but with a different texture sheet through colour and emblem.

These are the examples of karts i'm thinking of designing, and will try to use these in my futuristic theme to create a well modeled and textured car to use for both units in my UDK racing game.