smib
is a big honkin' homo
If by silly limitations you mean soft/firmware implemented to lock down hardware, the answer is no. A said it will work with an aux. port, but may not work with a USB port built into the head unit, though it likely will. Also, most head units with a USB port can play directly off a flash drive, and the Sansa(as well as most others) players can be set to act as a normal storage device, so car stereo integration on some level shouldn't be an issue.