See also:

Capacities
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In the cargo area
Open the cover on the right side trim. Information on the fuse types and locations is found on a separate sheet. ...

Fuel tank capacity
Approx. 22.5 US gallons/85 liters, including the reserve capacity of approx. 2.1 US gallons/8 liters. X5 xDrive50i/X6 xDrive50i: reserve capacity of approx. 3.2 gallons/12 liters. Refuel promp ...