Mountain Driving

Enblethen hit key points. Having lived decades at 9000' I'd add on ascents be happy with slower speeds. Those 18 wheelers in the right lane going 5 or 6 miles an hour, you may have to do that, depending on how your gasser behaves at altitude. You will lose approximately 3% of your horsepower for every 1000 ft above sea level. And I would reinforce the idea of using your transmission to hold your speed on the downgrade. Keep your foot off the brake. When you get up a few miles an hour faster than you like, that's the time to use the brake just to bring it down four or five miles an hour. That way they will be available should you need them in an emergency. Nothing worse than having hot brakes fail when you need them the most. An aside, those emergency off ramps will just about tear your vehicle apart if you have to use one. Truly last ditch option.