There’s only one engine available with the 2012 Toyota FJ Cruiser but your mileage can vary depending on whether you have a rear-wheel or all-wheel-drive model and whether you choose the auto or stick.
The rear-wheel-drive FJ Cruiser, which only comes with a five-speed auto, will see you return 17/22 mpg city/highway and 19 mpg combined. Add all-wheel-drive and you’ll see the highway figure drop just 1 mpg. Given the marginal difference in fuel economy between the two, we strongly recommend you opt for the added traction of all-wheel-drive.
Contrary to what you’ll find in most other vehicles, the auto is the more fuel efficient option here. If you choose the manual, you’ll see your mileage dip to 15/20 mpg city/highway and about 17 combined.
Those are pretty dismal numbers for a mid-size SUV, especially if you’re only using it to cart the kids to soccer or picking up the groceries, but if you need a serious off-roader the FJ isn't any worse of a choice than similarly-capable models like the Xterra or Jeep Wrangler.