In our scenario we want to enable the choice of car engines between six (6) and eight (8) cylinders. The advantage that the Bridge pattern brings to the problem domain is that it can be dynamically configured to work with either concrete engine type. We have concrete engines as types instead of a factored engine with a cylinder attribute for example purposes.
Because the base Bridge calls cloneImplementation in EngineBridge the Prototype pattern is suited for Engine becuase we want to create a Engine based on the prototype that the Bridge is responsible for.