I've been experimenting with crushable cars. I had to reverse engineer DiggerFan's and make them from scratch. I haven't noticed much (or any) of an FPS drop, so I've decided to add them to all of the tracks in the Powertrax series. The way they launch trucks in the air due to the springiness is really fun and realistic. The only problem I've encountered thus far is when loading some tracks, the cars fall through some track mesh surfaces, down to the heightmap; but for some reason they worked in this first track. For the second track, the dirt they are sitting on is barely above the heightmap level, but you can see how they are somewhat sunken into the dirt rather than sitting on top.
If someone can help me fix this problem, and if DiggerFan doesn't mind that I used his .load file as a template; I'd like to release these in the scrapyard for everyone to use.