well, if I don't screw with the shifter (bad habit of throwing it into 1st at lights when ricers are next to me) I get usually get 11-13 in the city... last time I drove to San Diego from Vegas it was near 18mpg out on the highway .... and a lead footed it most of the way even, Vegas to San Diego in 4 hrs.
ha, not bad. i must admit i am guilty of taking the car out of overdrive at lights....whenever a little civic or neon pulls up with intent to get killed by a mid-90s family sedan.. but as far as the gas mileage goes, thats pretty good for a truck. the lumina only averages about 20 mpg so thats really quite good for a big ole Sierra.