My auto road experience was actually a bit scarier than necessary due to my own absent mindedness. I do have acrophobia and get a bit white knuckled on this kind of road anyway (I've driven the PCH along Big Sur a couple of times and the auto road up Mt Rainier and had the same issue). In this case there was an added factor. We had decided to drive up the auto road (for the first time) and park at the Cow Pasture and hike across the Alpine Garden. We were driving the minivan and about 1/3 of the way up I looked down at the dashboard and the low fuel warning light was on. AAuugggghhhh. Can't turn around now. Am I going to make it!?!? We made it up to the Cow Pasture (which is about 1/2 mile from the summit) with the fuel needle well below empty now. It had occured to me that the incline we were going up might be causing this but that didn't stop me from being freaked out. We went ahead with our hike which turned out to be great. Hard to beat a clear sunny July day in the Alpine Garden. When we got back to the car (without hiking over the summit) I decided to just head back down rather than going the extra mile up to the summit and back. Of course all the instructions say to drive down in low gear and use the brakes minimally. But what if we run out of gas!?!?

No power steering!!!

No power brakes!!!

We might die!!! So - all the way down in neutral with my foot on the brakes. Had to stop at every turnoff and stop for 15 minutes to keep them from catching fire. Of course I'm sure everyone can guess the end result. We got to the bottom just fine and then drove the additional 10 mile to the nearest gas station. Based on what it took to fill the tank it appeared that there were at least 2-3 gallons left. Just another in a lifelong series of my boneheaded moves.
By the way, if you aren't afraid of driving the auto road (and have gas in your tank) the access to the Alpine Garden via the auto road makes for a great hike near the summit without having to do the whole mountain. Probably one of the best ways to get small kids hiking up in the clouds.