The railway costs about $37/person in November and more than $60/person the rest of the time.
The auto road is $28 for the car and driver plus $8 per passenger. I've driven up about a dozen times since 1987. First time was in a crummy Ford Tempo and the last time was a GMC Yukon XL. I've never had any sort of a problem on the road.
It isn't a difficult drive, there's a lot of BS rhetoric on the CD, and it was probably true back in 1965. But a modern car? The radiator is not going to explode if you drive up with the A/C on and the brakes aren't going to catch fire so long as you don't creep down riding the brakes all the time. Here's a Mustang GT descending in summer 2012, yes I was driving. Just use a low gear and brake when the speed gets up too high. There are plenty of places to move over and admire the view.
http://youtu.be/DC6xjIFN6Jg