This bug has a simple repro, so I'll just post that. Let me know if you need more details.
1. Hop in the PRT and start driving
2. Open the datapad via E or one of the app key mappings
3. Press "Esc" to close the datapad
4. Attempt to steer, brake, accelerate or turn.
Result: no vehicle control
Woraround to regain vehicle control: open the datapad and press E to close it.
Customer support service by UserEcho