My 42 mpg was a couple years ago or so on I-75 mostly going from Kentucky down to Deals Gap. Running 80 plus. Now to be fair, the whole tank was not run on interstate, but on back roads. I measured it 3 or 4 times over the coarse of that weekend,which included riding in the Smokies and the result was similar. I wasn't hot dogging it as I had a friend along on his Harley with a passenger.