So I'm pretty keen to build a racecar (probably an R1 powered locost) but before I jump in the deep end I thought I'd take on something smaller to test my fabrication skills. I've started by doing some modelling on computer - this amazing racecar building site gave me the idea and motivation. Already the design in my head has changed from a side-by-side arrangement to having the motor and axle mounted on the rear suspension subframe.

So given I've already changed my mind on this design it's useful to post it up as I'm sure the final revision will have varied from it greatly:

I'm using Blender to model the parts to scale thanks to these great precision modelling tutorials. I'm sure eventually I'll have the need and budget for something as comprehensive as SolidWorks but for now Blender units == 1cm is working great as you can see by my ATV driveshaft model: