I've been very disappointed with my 2010 Enclave mileage. I am lucky to get 18mpg with mostly highway driving. Even on a trip from MN to FL it wasn't any better. In my previous vehicles I always got the rated highway mpg or better, so it's not my driving style. I believe the six speed automatic is BAD for mileage. It's always downshifting. You can be cruising at 55mph and just the slightest touch of the gas pedal will cause a downshift.