Hey!
The rules are intended to allow you to shift up by 2 degrees on the drivers turn - once for free (similar to a moving on foot) and once in place of your action.
I've been talking with another GM who uses the rules a lot, and they suggested that it's doubled. So you can do it up to 4 times (2 movement, 2 action). I really like this and think it allows the driver a bit more freedom on their turn.
In hindsight the NOS bonus is badly worded. It was intended to let you go over your vehicles max speed for the duration but not just flat out get you there. I'll have a look at it for the inevitable 12 month anniversary errata update.
Appreciate you taking time to comment!