40 to Grand Lake Co.

SDM wrote:
How is the highway 40 from I-70 to Grand Lake. Mountain passes and curves?

Mountain Pass? Check
Curves? Check

It is not overly difficult however. It's 3 lanes all the way -- 2 lanes climbing on both sides. Four switchbacks on your way up, a parking area at the top of the pass where one can park and hike even higher and have some fantastic photo ops.

Of note on the downhill side north of the pass, there's a couple of switchbacks and then a fairly long downhill that's not so curvy. Don't be fooled by that! Toward the bottom there's a couple more switchbacks and they sort of sneak up on you if you're not paying attention. Past those last couple of switchbacks and then it really is rather smooth sailing in to Winter Park.

And a Duramax should be fine at 11,3. I was up over 12K with mine a few weeks back and it hardly noticed the elevation change. Sure as heck was a lot better than doing the same thing with a gasser Tahoe!