The auto will be the biggest hinderance to your MPG. I regularly see up to 5mpg difference between auto and manual s10's when people list their mpg on the different s10 forums. Mine was a 4banger too which helped out as well with no AC or cruise or anything else fancy, pretty much the only option was 4x4. A lot of people say 4x4 hurts milage but looking again at the listings on the various s10 forums I can see little difference between the milage of a 4x4 and 2wd.