They probably don't roll as high as I do.

The 12 mpg to work and back doesn't bother me. Its 3 miles in traffic and takes about 15 minutes to get there, 4.5 miles back home.

"Econo mode" is crap. Best mileage gains is usually on the highest setting. I think mine's on 100ish hp setting. Never had a problem with a 7.3 blowing smoke except when shifting (manual). That was with 60-80 hp programmers of various make. Only time one blew much smoke was when the wastegate spring fell off. Get a wicked wheel.