Tested in VRChat 2020.3.1 [956]
After one of the most recent updates to VRChat I started noticing that while driving vehicles faster than around 100km/h, your avatar would freeze in place and only way to fix it would be to slow down the vehicle.
The issue can also be triggered by moving your playspace further than around 0.5m away from the center of the VRC_Station you're sitting on in X or Z axis. On Y axis you can move as far away as you want.
I assume the velocity-based freezing is caused by the game seeing your avatar further than around 0.5m away from the station during update as your velocity at around 100km/h is roughly 0.5m / frame
Same issue happens in both VRCSDK2 and VRCSDK3 worlds.