Try steam trucks. One place I was at had 3 of them. Over 20k hours and under 50k kilometers on each of them.
If you are looking to buy a used truck, getting an ECM dump is one of the thing you need to do. You will see all the particulars about the truck including idle percentage. In addition to getting a dyno with blow by test run, Oil Analysis on all fluids, running a RigDig report and getting a mechanic you can trust go over the truck with a critical eye. Not necessarily in that order and yes, you may spend the money to do that and find the truck isn't worth buying. But better that buying the truck and then find out that is wasn't worth buying. Good luck in your search.
I've ran 7 RigDig reports, and these are the (2) trucks left. As KR would say, I'm looking for a reason to NOT buy. I thought the high Idle on the 2020 was the reason, but then I thought maybe with it having 78,000 miles less, and having 2-year newer technology, that would offset that.
Miles/hours does nothing for me. The condition of everything else would be what would cause me to choose one over the other.
To give you something to let you know both those trucks have idled a ton. My truck which has a generator and hardly ever idles has 789346 miles with only 14625 hours, hope this helps.
Lowest trucks I've seen so far for engine hours are the 2017 Walmart trucks hitting the market now, in the mid 500's have around 11000-11500 hrs. Everything else I've looked at, anything in the 15000 hr. range is low. Most are 18000-20000.
Sorry about the vague description. 14,600 hours and 436,000 miles on a x15, show that the truck has been idled a lot?
I ended up finding a 2020 Cascadia with 419,000 miles and 8025 hrs. Has a TK APU, and Optimized Idle. So very low engine/idle hrs.