What a debacle! I purchased a 2010 S-Class 4Matic Saturday with 45K miles on it. Test drive went fine. After I left the dealership I went to change lanes on the highway and nothing happens. The steering wheel started spinning freely, turning 360 degree with no action from the front wheels. The power steering system and skid control indicator came on prior to the loss of steering on the display. Scared the crap out of me.I hit the flashers and slowed down (freaking out) I was able to get a little tension to the steering wheel and drift off to the shoulder. My greatest anxiety comes from the fact that I was on my way into the city(heavily populated) had I made a turn and the car surged forward I could have hit someone or something.
Dealer brought me a fairly (S550 4matic ) to drive temporarily but now I'm staring at the steering wheel often. Based on some posts I've read that this is akin to gearbox issues associated with the spline from the steering column shift etc. Either way, I'm not sure I want this car even if it's fixed. And to my understanding the repairs of this problem is fairly comprehensive. I've been driving these cars for 20 years and it seems once you have a ghost in the machine it continues to haunt you. Thoughts? I'm not even sure if the dealer retrieved the car yet, but it will be in an interesting conversation.

Any body experience total failure of S550 4matic, where the wheel spins freely and no control of steering?

 

Man you saved yourself from a disaster i guess. Get that checked immediately otherwise it is definitely gonna end up terribly.

 

I have horror stories about that generation S class beautiful car but plagued with simple mechanical problems good luck

 

Sounds like a mechanic could have left something loose. Was it a broken suspension component? a ball joint, a tierod? Or did you loose power steering fluid? Maybe the steering shaft came apart, very unlikely though. Could be the steering rack itself.
Let us know.