The engine pre heater is mainly sold on cars for Sweden and north USA and Canada, they sit under the offside front wing and run on diesel fuel,, they have a remote time clock so that the car will be warm when you need it and most are made from Webasto
http://www.webasto.co.uk/am/en/am_automobile_3177.html
But we are in UK, does this means the russian site info is not correct.
Not at all there are quite a few over here, and very nice to have,I could have one on my SL and most of the larger MB's are made to have this
Your SL got everything like a Merc showcase. What year is it and has it got rain sensor?
I thought the rain sensor is the black blob beside the windscreen jets until I realised that the bunch of clear LEDs above the rear view mirror. I thought these are distronic until I realised it located on the grill.
My car is an early one though it does have every possible extra with the exception of the engine pre heater that is not a normal one.. If I put one in it would get rid of my only blank button on the dash, for I hate blanks more than anything else.
The blue circle in the center of the screen is auto wash (never use Rain X) and the distronic is the plastic face over the grill star as in my avitar,, on the latest big cars it is behind the grill