Most class b rvs are 70 to 100 percent fully loaded all the time and make long trips. Let's not compare their performance with the performance of vehicles which are used for stop/start driving or towing unless we intend to use the van that way. Our first transmission replacement for our 2004 2500 Sprinter/Sportsmobile was at 240,000. miles. Since 1976 I have had 4 Chevy 3500 gas vans and one Chevy diesel van. The automatic transmissions had to be rebuilt soon after 100,000 miles. These were fully loaded 30 percent of the time towed, occasionally and empty 30 percent of the time. I have no complaints about the Chevys considering the way they were used but I love the Mercedes based diesel Sportsmobile.