Just starting on some mods for my '06 VW Golf TDI. Been working on the nut behind the wheel for about a year now since I got the car, and have seen steady improvements -- I'm up to a bit over 50 mpg on my last few tanks. Time for some aero mods.
First up: rear wheel fairings. Went with aluminum flashing to match the silver car. The flashing is screwed to a triangular frame of aluminum bar, which mounts to the wheel well at three points with wing nuts for quick removal. I didn't want to drill any new holes, but was able to mount 5 brackets on existing screws around the edge of the wheel well -- three to bolt the fairing in place plus two tabs to hold the edges flush with the body. Fairly pleased with the way the turned out.... performance effects tbd.
Next up: pizza pan wheel covers, and a removable kammback that I'll strap to the hatch like a bike rack for longer highway runs. Also thinking about a grille block and partial belly pan.