I am thinking about purchase the Thor Challenger 37, I was wondering if you own the Challenger model could share your experience of the RV going uphill in Rocky Mountain region ie. Colorado, etc... Was the RV have enough power to go or dragging... also if you could share your experience about the average gas mileage on normal road condition.
First off plenty of power. You can read my post about our trip cross country with a portion of that time in the Rockies around Yellowstone. We have a 2013 Ford Explorer as a toad and never had a problem. You should seriously consider a supplemental brake system like the BrakeBuddy for the down grades. I had a Blue Ox AutoStop (should be called AutoJunk) and half way through the trip bought the BrakeBuddy. We now have complete confidence on any down hill grade.
MPG is conditional answer. Most of the time when I refuel my Distance To Empty (DTE) says 540 miles. That indicates about 6.9 miles. However, in California (where the max speed for vehicles with a tow is 55) it was about 580 miles for a about 7.2. Likewise when you are asking the V10 to pull a 15 mile 6%+ grade, look for about 6 mpg.
Best speed for best mpg is definitely 58 mph. Best speed for cruise control driving - 68 mpg. About a .7 mpg difference. A trade off.
Hope this helps.
US Army Retired - Loving The Road Trip