We're mid 20s (25-27 if flat highway, 22-24 mountains) on the highway and 20-21 mixed (mostly around town). When I drive it to/from the office (surface streets) for a whole tank I'll end up with 18s which isn't too bad for a heavy SUV--plus diesel is cheap here. I had an Escalade before and good lord that pile of crap got like 10-11 around town.

Get a really clean '13 and toss a burger tuning JB Diesel chip in it for $200. It's plenty!