The wikipedia car is the same vehicle. The plates are the same. It's only armoured to handgun-class and is ridiculously expensive. For $650,000, you could buy a fully protected Audi, BMW or Mercedes.

I've seen the armoured Silver Spur as well. Only embassy cars are armoured by Rolls-Royce. They seem to max up at B6-level. Most armoured cars are B6/B7, but all the factory-armoured I've seen is B6 only.