I know everyone and their mother has made an X-Car, but I haven't, so this will be my attempt. It's not going to be very long, but it will be extremely intense. So for I have a 90 km/h launch, 4.2g turn, a zero/floater roll, and an -1.2g airhill.
http://www.NoLimitsDevCenter.net/p4465
Let me know what you think. Testers welcome.
Enjoy!