RC:
The RS6 doesn't exactly have the same body as the normal A6, you can recognize the RS6 from a mile away. 
you can - I can, majority of people can't!
I also agree with Herbaliser: I can order a brand-new RS6 Performance to my specs at my local dealer for a MSRP of 160k EUR, let the dealer register the car to the dealership, me driving the first 1000 km with it (run-in), dealer gets two months and another 3000 km with the car (testcar) and I get the car for 120k EUR in the end, with a five year warranty. Not even talking about the often very good lease conditions because Audi uses Volkswagen Leasing/Financial.
Fair enough. If the lease is comparable to a lower priced car, why not. It for sure is a great family sedan!
I do not try to compare an Audi RS6 to a Panamera (the new Panamera interior is already miles ahead of the current RS6 interior) but performance-wise, the RS6 Performance is actually a tiny bit faster than the Panamera Turbo, so they are quite comparable. Especially since the Panamera would cost at least 50k EUR more.
Trust me - I was half an hour in the Panamera interior. Yes it looks great, but those buttons are just not my cup of tea. No touch feedback, you can't easily use them. Audi is doing a great job with the interiors and in the RS6 the materials used are top-notch.
What I am trying to say: Prices got out of hand. Now with the low interest rates and people not knowing where to put their money into, luxury cars have good sales figures. Although...the first Panamera generation sold pretty slow in the end, I just hope it was just an end-of-production slowing down and not something else.
There we go - this is really true. They are going extreme. But there is a level of buyers which easily can afford those. The production of most of those luxury vehicles are sold well. Car manufacturers need to make their stakeholders happy, not their clients - period!
