When my Samurai was stock, typical mileage was 26-27mpg. It didn't matter if it was in traffic or flat out on the freeway, it was always the same; I think this was due to the lack of aerodynamics. My best tank was 32mpg, but that was drafting a semi down I-5.
I will say my Samurai hasn't bee stock in about 20 years; this was back when the 55mph speed limit was the rule in most places, so I rarely had it above 65.