I've been getting a range of 315 to 336 miles per tank over the 4500 miles I've put on my X5 4.8 in the 2.5 months I've had my 2008. Lately my average has shot up to 16.1mpg, but that's because I put 2400 highway miles on her at the end of December. This week (with mostly city driving) it has dropped back down to 16.0.