Hey Pandorea, I play through steam so it's up to date I think. Build is 3417012, version 40.43.
Playing last night I started the server and tested vehicles without the second controller/player and all was well. Cars moved for me and I saw no signs of any problem. Had the second player log in with the controller (split screen) and the issue resurfaced immediately. Same thing, engine revs, squealing tires but no movement. Second player had no such problem.
Cyrix got a reaction from Pandorea in Cars don't move / Split-screen using 360 controllers