My old 99 Trooper had 4.30 gears, as do all 98+ Troopers. It would get ~17 hwy mpg, give or take 1.

My RS gets around 16 hwy, not bad for a lifted Trooper with 35" balloon tires. Sometimes it does better, I got 20 mpg from Grand Junction to Sterling CO on the way back last year. I always get better mileage going through the mountains for some reason. I think the manual tranny helps some, but I have the EPA est mpg sticker that came with it new, and the EPA hwy estimate is only 17 mpg (in stock configuration of course).