This is a hard question to answer as the gas mileage varies quite a bit depending on a few things. My Dad and I both have one, I'm getting about 18 MPG mixed driving, where he is getting about 21 MPG. The one big difference, mine is automatic and his is a manual trans. Additionally, the Jeep XJ series has a lot of quirky, but not serious issues, which can seriously affect the gas mileage. A couple of these are the crankshaft sensor and the oxygen sensor. The crankshaft sensors are renowned for going bad, and as they start to go they will cause misfires and eat up your gas mileage. Hope this helps.
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The EPA mileage estimate for the 2014 Jeep Cherokee is 22 mpg in the city, 31 mpg on the highway.
The EPA mileage estimate for the 2001 Jeep Cherokee is 16 mpg in the city, 21 mpg on the highway.
The EPA mileage estimate for the 2012 Jeep Grand-Cherokee is 17 mpg in the city, 23 mpg on the highway.
The EPA mileage estimate for the 2010 Jeep Grand-Cherokee is 16 mpg in the city, 21 mpg on the highway.
The EPA mileage estimate for the 2004 Jeep Grand-Cherokee is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2013 Jeep Grand-Cherokee is 17 mpg in the city, 23 mpg on the highway.
The EPA mileage estimate for the 2011 Jeep Grand-Cherokee is 16 mpg in the city, 23 mpg on the highway.
The EPA mileage estimate for the 2005 Jeep Grand-Cherokee is 15 mpg in the city, 21 mpg on the highway.
The EPA mileage estimate for the 2007 Jeep Grand-Cherokee is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2014 Jeep Grand-Cherokee is 17 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2001 Jeep Grand-Cherokee is 14 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2006 Jeep Grand-Cherokee is 15 mpg in the city, 21 mpg on the highway.