Thats a beautiful drive through that area. we have been through there twice a few years ago. we stayed at the keystone resort both times.
really amazing how they built the highway through the mountain side with out tearing up things and leaving it all looking natural.
we had our 85 300D turbo, cali. equiped trap oxidizer. etc.. what a dog it was up at that altitude, no get and go, even down hill. pretty bad when I got beat by a 61 VW down hill

.
the second year we removed all the cali junk and changed it like a 83 is set up. A totaly different car, went like a Corvette

. don`t remember the milage we got back then, but was an improvement after the change over.
Charlie ☺