When you're a queen and you're visiting Germany of course you won't drive a lousy BMW 7 Series or Mercedes-Benz S-Class. You just bring your own Bentley State Limousine for transport!
Queen Elizabeth uses this car for quite a while already and that can be seen. The high roof line and the exterior of the car make it look very old-fashioned, but that does actually match with Queen Elizabeth in the car. She's on the throne for such a long time that we guess that the Bentley will be gone before she will step down from the throne. To make it all look even more special, there's a police bike convoy in front and behind the car, all to make sure that the Queen stays safe.