It almost never goes above 2100-2200 RMPs when I drive my fully modded 2001 Tahoe with 4.10 rear gears, a 4L80 trans fully built and a 2800-3200 stall converter , and a built 6.0L with heads and cam gets better MPG and I only have a 20 gallon tank and have to run premium pump gas. I don't get it. My RMPs in my Tahoe are like 1550 RPMs at 30 MPH. And my 2001 Tahoe does better then my wife's. he'll my buddies 2009 ford F-150 4X4 with a lift and 20's with 37X13.50R20's and stock gears gets 14-16 in town WTF!