Semis are no different. Awhile back at local Freightliner dealer, they had a fair amount of newer trucks in lot for "X" service. Service writer told me that 70% of them were for DEF issues. Some of the newest ones are or seem to have a lot LESS problems. So like pick-ups, the engines, suspension etc are all AOK. It's the DEF side of things that one gives a bad rap to "X" mfr.
Like I was told back in march of '12. When the DEF works, trucks are great. When not, biggest POS. Thank you tree huggers. My biggest fear is when (in our case as RVers) the warranty is up and DEF goes south, looking at coo-coo bucks for repair!!