We have a 2012 Thor Challenger 37 foot model (actually 38 feet long). Drives great and quiet and very stable on most roads, but it is indeed noisy climbing and especially in the mountains slows down quite a bit. But the engine has been reliable, and we love the floor plan and looks of the interior. So once you're at the campground, just as nice as most diesels, and considerably cheaper for the same quality interior. But in the mountains I've got to be honest - it sure would be nice to have a diesel.