I'm not aware of any rules of this, but if you are constructing a new driveway, don't forget to allow for the width of a vehicle with the doors on both sides open, plus room to manoeuvre around with say a wheelie bin ! I'd allow 4m if I had the room. Don't forget to take into account any areas required for reversing/turning around - it's much easier to drive *out of* a driveway pointing forwards than having to reverse out into the flow of traffic.
When designing single track access roads, I often use the width required by the emergency vehicles (3.65m) as a guide and just round it up to 4m for ease of measurement.