I completely understand the thoughts of all the people in this thread who are 'for' telling the insurance company about it but I'd like to highlight something:
We are car enthusiasts so we probably understand cars and their derrivations more then (say) 50% of the drivers population in this country. Most people buy a car, then inform the insurance company of what the car is and that's that. If the insurance company is then reluctant to pay out then I honestly don't think they'll honour their decision all the way into court, they might try to be difficult about it (I've seen this on numerous occasions with friends), but if they dont have a leg to stand on they
will pay, simply because they are legally bound to do so.
Now, in the case with your car, if it honestly left the factory in that fashion, then it must be documented somewhere, because I do not believe you are the one responsible for declaring what the car is when its manufactured, Mercedes are. I agree that you are responsible for telling the insurance company of anything that you see out of the norm, but the only thing I see out of the norm here is that you have a gorgeous looking CLS that has left the factory with extra options, and was paid for and collected like that.
If the car didn't leave the factory like that, and these bells & whistles were added later, then the owner who did it at the time would have definitely been responsible for telling the insurance company as they are exterior modifications which are at the risk of damage in an accident and I am completely FOR that. Be careful when telling the insurance company, because quite alot of them will quite happily cancel your insurance cover on the spot if they fear that the car is modified, which yours is, but its a factory or authentic modification which Mercedes offer. Its not like you've bolted a supercharger and IVT's onto your engine.
Everything I'm saying here is up for debate, but this is how I feel, because quite frankly I absolutely detest insurance companies in general and I refer to them as 'legal thieves'. Some insurance companies even want you to declare mods INSIDE the car, like a stereo system or whatever. What next? Declare what clothes you wear while driving in case it is the cause of an accident?
Only my 2p.