I've never seen those kinds of bumper guards. Because of this, I feel they are not original equipment. Perhaps the experts can chime in here (like Douglas, among others).
However, they look like they were always meant to be on the car.... reminds me of the full rubber strips that Mercedes added to the 280SE bumpers after the all-chrome bumpers on the 220SE/250SE cars. Instead of full-length rubber strips, yours are sleek little bumper guards that might serve a useful purpose whilst keeping the streamlined original look of the car.
Do you have them on the rear bumpers as well?
My car doesn't have the ugly US-style bumpers, but I often think of adding something to provide some measure of safety from stray parallel-parkers. The bumpers on your car look very nice, and I may yet try it out on a spare set of bumpers I've lying about.
I would love it if you could perhaps post more extensive pictures of your beautiful car in the picture gallery? I'm sure many of us would readily admire it here. In any case, thanks for posting this one!
Best regards,
Waqas in Austin, Texas