i took my 96 bmw 740il out to california about 4 yrs ago.ran a consistant 23-24 all the way outto san berndino and then and back to lead colorado.i filled there and got on the interstate back thru nebraska and doing 85 that tank returned almost 29 mpg.don't know if it was just coming down from the elevation or what.next tank was also above the rest at around 26.after that it settled back into it's 23-24 range.one thing i liked about that car is the vacuum gauge.doing 60 or so gauge showed in the 18 range.doing 70 it showed in the 23-25 range or more vacuum.i would agree these german cars were made to open up and run.