I once rode my dirt bike up a fourteener in the Mosquito Range. It was a 550, 4 stroke and it just barely had the power to make it to the top. The air is rare up there.
And just think...it's another 3000 ft. just to get to the base of Everest.
Just how did they get that Toyota to run that high up?
(specially designed diesel or something?)
In college I dated a girl from La Paz, Bolivia. The city is at an altitude of 13,000 feet. She said that the air was so thin there that you could hold the tip of a lit cigarette against your finger for several seconds and not burn yourself.