I have had my new AT4 with the 3.0 diesel for less than a week. Put 500 miles on the truck mainly on the highway bringing back home from the dealership. My wife drive the truck home and stunk up the whole garage with a hot smell. Pulled the truck out of the garage and got an emission error code that stated limited speed would be allowed in 179 miles. Took it to the local dealer. The dealer pulled the code and sent it to GM and they would not release the part without the code repeating. Said the code was a valve in the emission system. Left the car with the dealer and they drove it and the code reappeared. The dealer stated gm engineering is very interested in the issue but still have not release the part. So I have a brand new truck I can't use. My buddy tried to talk me into the RAM diesel. Maybe should have listened. More than a little frustrated that a $60000+ truck can't get repaired. Anyone else with this issue.