I believe it's only a 'development' version. The later models will have laser tracking for greater accuracy.
From what I have gleaned they will only fire enough rounds to slow a vehicle down to a safe speed rather than destroy the car totally or kill the occupant.
The UK government felt that they may nor be able to pass them through law if people were being directly injured by the device.
Don't forget we do have some excellent American members that might not understand our humour. 'friendly fire' is a sad reality of what happens when brave men go to war. Let's keep this funny and not accidentally insult our colleagues from across that little lake.