I have a Mercedes-Benz SLK200 and I thought "K" of SLK stands for "convertible" without deliberation, because "C" in English words are often replaced into "K" in German words. If it's translated into French, it's Cabriolet.
I knew on strange occasions that the car which Lupin the 3rd, a hero in Japanese manga, uses was Mercedes-Benz SSK and it was also convertible. I'll show you a picture quoting from the net. Seeing the style of his car, I thought "K" of SSK must also stand for "convertible".
I investigated several websites concerning cars for confirmation, and found my idea totally wrong. "K" is the abbreviation of "kurz" in German, which means "short" in English. SLK seems to be the short version of SL.
on strange occasions ひょんなことで