You will get answers all over the board on this question. Anywhere from about 14.5 up to 23 mpg. It really depends on lots of factors. You may want to consider using the search feature above (in the gray band across the top) and type in MPG or Mileage. You will get many, many threads. Read away and enjoy.
DEWFPO
__________________ 2007 FJ, 5AT, Sun Fusion Yellow, CQ, UP, GY, RB, 2Q, EL, VS.
"Wanted - young, skinny, wiry fellows, not over 18. Must be expert riders willing to risk death daily. Orphans preferred"
Original newspaper add placed by William Hepburn Russell, founder of the The Pony Express
My best: 22mpg. 100% highway at around 68mph and gentle acceleration on premium fuel.
My worst: 14-15mpg. All shorter trips in and around town, still not accelerating hard, on lower grade gas.
If lower mpg numbers are gonna worry/depress you, definately use premium.
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2007 VooDoo 4x4 Auto - LOADED
OEM Roof Rack, Rock Rails and Skids
Unknown brush guard and tail light guards
TRD Exhaust
Add'l 12v outlets
Scuba Mod
08-09 side sun visors
Power rear window mod
Backup Camera w/ 7" monitor
Once you add larger tires, more weight in the form of bumpers or skids, lights and larger roof racks for more air resistance, then it will go down quite a bit.
If you are worried about gas mileage with an FJ Cruiser, you probably should buy the RAV4. FJ is not all that great on gas considering it weighs in at 5500 lbs. dry.