My '03 SO 4x2 gets between 21-23mpg during mostly highway driving, dependant on the speeds. Freeway driving (70-75mph) gets me 21, and normal highway driving (60-65) gets 23. I just drove 350 miles of intertstate on Friday and the overhead averaged 21. 6. Around town it drops to around 18-19mpg.
I upgraded from a 1st Gen Club Cab, and the difference is night and day with less noise, a smoother ride, better brakes, and good access to the rear seat. I really enjoy my '03, and it is the most practical vehicle I've ever owned.