Are the 2018 Kenworth T680 with cummins x15 engine a good reliable truck?

I wouldn't buy a new one. I did buy an out of warranty one and did a little snipping. Coming up on 100,000 miles beyond purchase point, and it's flawless.

 

I had good luck with a new 2016 T-680 and the last isx model before they went x15.. great truck overall. I can imagine the X15 is now even better though. I drove mine and traded it in at 500k miles. Never had issues with it. Never seen a check engine light in those 500k miles.. i did all my maintenance on time and according to the scheduled intervals. Used to get great MPG Avg at 64-68mph (2:64 rears) If you buy it new just stick to the maintenance and change oil on time everytime and don’t worry. Good luck to you