LewiSS

Actually, going west out of Denver you can get below 2,000 ft altitude before a refuel somewhere in Kansas. That said, I have never had a fuel issue on that drive with any car I've had in the 20 years I've been in the Denver metro and driving I-70 east into Oklahoma. I do tend to get "real" fuel as soon as I use up the altitude mix going east, and try to fill up near the Colorado border to have some non-oxygenated fuel for the final leg home (it gets better mileage).