It depends on the size of your tank.When I put my fuel cell in , I lost 3 gallons of capacity.With my trooper and the 3.4 with 33's , and lifted , I am getting about 230 KM on average to the tank , and its 19 gallons instead of 22.I haven't done a lot of highway yet , so not sure what I am averaging for highway , but I would say its not a hole lot more then what I am getting in city.I think it was around the 70 mark for a full fill on my tank if I remember correctly.I usualy fill it again before it goes under 1/4 now.

1996 Jeep Grand Cherokee 5.2 with mods.Hughes Air gap intake , 52MM TB , ford injectors, 2 3/4" lift, Doug Thorley headers , HID headlights with LED , HID fog lights , glow gauges , a few others