it is always good to hear about new businesses accepting bitcoin but Mercedes Benz accepting bitcoin is a small one in my opinion because it is not a day to day thing and most people don't want to spend that much bitcoin anyways.
and Dell has been accepting bitcoin for a very long time. it is not a new thing.
Every company that accept bitcoin payment is a good move for development, not everyone will spend their coins to buy a luxury car which cost Million of dollars using bitcoin, because they could charge more than the current market price in case of precause from fluctuate. Moreover, if the price increase after that, I may say it's a bad decisions to spend bitcoin (% charge) more than the current price instead of convert bitcoin into fiat and buy the car. At least the rest of your coins will grow up again.