Is there a difference between the tuning of the 17 and 18 auto?

Im debating getting between a 17 or 18 manual trans, or an 18 auto trans. Why does the 18 auto get less mpg than the 17? Ive test driven both and on the 17 I noticed the typical finicky gear searching, but the 18 seemed ok. I asked the salesman if that was the case, and he said, "I think the 18 just has more power." haha

 

Looks to me like a reprogramming of the Trans is also showing up in lower mpg . I will bet it will not go into 6th gear at 35 mph in the 18 . This was a major complaint with the 16 and 17 models .
Edit , this is just a guess . I would like to drive a new 18 to see and feel for myself .