http://ecomodder.com/forum/showthrea...why-12732.html
This thread has some good information on the Beetle's unimpressive aerodynamics. The basic body shape isn't great, and an air cooled rear engine is far from ideal from a FE perspective. So I would say an aero rebody is a great place to start. I would also make it a point to get modern, LRR tires and an efficient engine.
An aero rebody is a very ambitious endeavour. I can only think of a handful of people on EcoModder who have attempted it. How far along into the process of planning and allocating resources are you?