When we only had two letters there were 999 cars out there with VD, but we don't have any WCs because the powers that be decided it was rude!
There also used to be a car here (think it was a Merc coupe) with FU2, there was also one in the UK with that number.
Another interesting point is that at one time my favourite beer manufacturer had a number of vehicles with KE0 (zero) as the first part of their registrations!