That lone bell tolling in the distance is the death knell for the BMW M6. Yep, everyone's favorite crazy-powerful coupe (or convertible) is ceasing production. At the heart of the matter is that big, powerful and thirsty 5.0-liter V10 engine-too many emissions, not enough frugality. And since the M6 uses much of the same running gear as the now-defunct E60 M5, the business case is looking weak. When a new M5 based on the F10 comes out, it will probably have a twin-turbo V8 that could kick out in excess of 550 hp. The demise of the M6 marks another end: BMW's expensive involvement in Formula One, from which this 500-hp V10 was derived. And the 6 Series in general is due for regeneration soon. But anyone with just over $100,000 to spend might still find the odd M6 or two in BMW dealerships for a while.