The next step as already mentioned could be reducing the drag created by the fenders and sharp angle flat wind shield. Best displayed in this photo. The car to the far right will be mentioned later.
History Dick Beith's 50th Anniversary Return to Bonneville - THE H.A.M.B. Build photos of car.
I like this idea of minimizing the fenders. A narrowed front beam is a common modification and easy to do. The salt flat car is narrowed in excess of 12”. 2-4” is what most people use for traditional cars. The 6-8” narrowed usually lack shock towers and are used by the extreme lowering or drag racing crowd. All are available for a price or if you have the skill you can do this yourself. The rear is a good bit harder and more expensive to narrow but it has been done up to 6”.
You could also remove the front fenders all together to get the Prowler look you want or all fenders to make a Volksrod.
Low Life vee dub club - Members rides At the bottom of this page is a Prowler type car based off a Super Beetle.