I dont think anyone has ever tuned an Enclave but having owned a 2011,2014 & current 2017 all three were ordered and exactly the same options the 2014 had the best mileage my 2017 fell under stricter emissions and mileage fell 1 mpg but drivability is much better. You should get 24 HWY, I did and traveled across the U.S many times while I had it.