I don’t understand tge “ upgrade” comment. Aren’t mileage rates independent of the value of the car? I will ask her when I speak today, as the “ladies” in my life are away on holiday and I’m rabbit, hamster and dog sitting shuttling between houses.However it cost her £"X" amount to upgrade so she should be entitled to additional help with fuel bills as those people are essential workers. Never mind the type of vehicle as they should be paid per mile as you still have running costs involved.