2-3 mpg is way optimistic <=1 maybe. There is really not much to spin there. Gains would also severely depend on type of driving. Stop and go would see more improvement than hwy. Easy test for people with hubs - lock the hub (make your truck essentially same as stock Gen 2), use a tank of gas, record results, unlock the hubs, use a tank in the same manner, record. 3 mpg out of 15 is huge. it's 20% improvement. Маnufactures would jump on such opportunity. They are continuously hammered with demands to improve mpg and here they miss su...ch opportunity. No way they are so stupid. Yet they seem to go opposite round deleting CAD systems. Like current Ram truck. Big benefit of manual hubs is if you say grenade your front axle/CV/diff you can unlock the hub and drive home as opposed to taking stuff apart on the trail.