My coach with the older engine is getting (slightly!) better mileage now that it has 6000 miles on it than it did when it was new. First Florida trip, with under 1000 miles at the start got 6.6 mpg. Recent similar trip got 7.1. Both times towing the same Jeep Wrangler. It would be nice to start at 8.5 and improve from there! Not going to lose any sleep over a couple of mpg but it’d still be nice.