I've done dozens of runs between Coppell, TX and Spring Hill FL (1100 miles). I can usually get to the FL house with one gas stop, but have YET been able to get back to TX house with one stop.

The 23 mpg comes with "prepping" the X for a road trip. I put on the non-staggered 18" wheels with 255s (inflated to 36 psi). Also worth noting, I have toe/camber set to minimum BMW recommended settings (less tire scrub during hwy driving). I've also added 10oz of Lucas Upper Cylinder Lube at EVERY fill-up for the past 100k miles (helps keep compression rings lubed, less drag on the cylinder walls & better sealing).

Of course, no AC, windows up, minimum braking and no rest stops during the 23 mpg runs.

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!