Model: X5 3.0i
Year: 2006
Cost Per Tank: $50-$55
Miles Miles Per Tank: 400-450
Current Mileage: 35201
Type of Driving: 50% Highway, 50% Local

Highway average: 21.5MPG
Local Average: 19.0MPG

The most miles I ever got on one tank was 481. On another occasion I had to put in 26 gallons to fill it up.

Interestingly, now that it is winter here in New England, my mileage has been lower by about 1 mile per gallon. The same thing happened when I owned a 2003 X5 3.0. Must be the winter gasoline formulations, extra engine warm time, etc.