Correct on the 1st point but the second is not true. You can purchase a european harness for your car and use the factory amp with the aftermarket system.
Just wanted to point out that both points are FALSE and you CAN buy an adaptor to work the steering wheel buttons. I did a post before of how I did it, there is also a training wideo to help. My steering wheel buttons are great now, as I can programe them to control whatever I feel like ! Deffinately get rid of the stock radio they are so dated, you can now have bluetooth, USB, SD , mp3 compatability etc etc....
(Full post is here
http://www.benzworld.org/forums/w208-clk-class/1395216-heres-way-keeping-your-steering-wheel.html)
I recently bought an excellent Sony MEX BT 3500 head unit for a great price at Halfords only £127 ! as I got a discount by reserving on line. The sound much sharper, louder and fuller then the stock CD as well as having a whole host of features that the stock stereo did not have, which is the reason I bought it.
For example I now have USB front input, ipod, Aux input, mp3, wma, etc etc compatibility as well as an excellent Bluetooth handsfree feature with built in mic so I dont need to ever touch my phone whilst driving, it just stays in my pocket ! and it also does Bluetooth music streaming to play your tunes too !
Now I knew that when I installed the Sony I would lose the ability of the steering wheel buttons, but not now I have added a PAC steering wheel adaptor controller. I live in the UK and had to order it from the US but it still only cost me about $110 all in !
For my CLK 2000 year model I needed to by two different adaptors and plug them together, one does the CAN BUS conversion (PAC SWI-CAN2) and the other is a general steering wheel adaptor (PAC SWI-PS) and the PAC customer services were really helpfull. Authorized dealer info
I wired it up and programmed it pretty easily and theres an online video to help too, in total it took me about 2 hrs to do. Steering Wheel Interface Training Video
And now I have full control again of my volume up and down steering wheel buttons and the left track up and down buttons too just like before!!
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