Colorado/Denver is higher altitude than Utah. I have done that drive several times and the car picks up in power after it's down at lower altitude. Nothing to do with E85.I have two now myself, both are 2015 C AWD models with the 3.6L. My daily driver has nearly 90,000 miles on it now, and the one I recently purchased out of Colorado has all of the Tech Features and less than 29,000 miles on it. It has the E-85 gas cap though. The way it drove back from the Denver area, it didn't seem to have as much HP or Torque. I was thinking it was probably because the previous owner was using E-85. Once I got it home after having put a fresh tank of E-10 on the way back it ran a bit better. Now I have put a tank of Ethanol free in it along with a bottle of Sea Foam.
E85 is proven to give you more torque than gasoline, not an opinion, it's just a fact. Don't start a debate, if you do, I will put a stop to it. I do recall some of your older posts.