Bentley uses a high torque starter which is more efficient. It can crank a larger engine with less draw...its equivalent to how gearing works where you can move a much larger object with less power depending on the size of the gear.

The H5 is used to crank the car and it has plenty of power to crank it with ease, which is why it sounds like it never struggles, unlike an H1 Hummer that has two batteries that it uses to crank the 6.5L diesel and still struggles with the 12v architecture that it was never originally designed for. The 24v Humvee cranks a lot better then the 12v civilian H1...