Depends on the year. The actual tank takes 19 gallons for models '99 and newer. As for fuel efficiency which is what I'm assuming you're more concerned about, it depends on the engine. I have the 4.0L and it gets somewhere between 16-18. Im not really sure because Jeep enthusiats such as myself don't really care about gas mileage. I heard the 2.5L isnt much more efficient, but a heck of a lot weaker, so I highly recommend the 4.0L; plus it is the legendary engine that never dies. You can check online for more details. Either way, I wouldn't call a Wrangler a big guzzler. Hummers, Suburbans, F-series, etc...those are big guzzlers. Jeeps aren't Honda Civics, but if you or your daughter is into Jeeps, get her that Wrangler. She'll love it.