i have a tj solara.
im getting 11 around town in granny mode. if i start getting spirited, it jumps up pretty fast so i keep that to a minimal wen im trying to save petrol.
on the highways, im getting around 7. if the roads are nice and flat, it sits at around 5. remarkably, it's not too bad at all. keep the air filter clean. half way on my last road trip, i had to pull over and tap it clean again cos the efficiency was going down. once i put it back in, it was nice and low again.