I have recently got a Range Rover with the straight 6 P400 petrol engine which is described as a mild hybrid.
It has the alternator and starter motor replaced with a 48v "mild hybrid starter generator" and a 48v battery. The starter generator generates electricity back into the small 48v battery during braking and then use it when starting the car and setting off. The 48v system which runs in parallel with a 12v system was developed as it provides a lot more torque than using a 12 v system.
