I am pretty sure that the taillight arrangement, with the left all-red and the right partly-white, is to provide a rear fog light per EU regulations. This is one of the few areas where I think US regulatory thinking (ie they're not required) is preferable to European. Because proper rear fog light operation is beyond the intellectual capability most drivers are willing/able to use, my observation is that they are mostly misused, in conditions where the visibility isn't needed, in which case they just make for more difficulty in recognizing whether a car is braking or not. They look to me just the same as brake lights. In the US at US speeds, one Volvo or Audi with a bright constantly illuminated red rear light, can be disregarded easily enough. Now imagine trying to drive 80 or 90 mph on the autoroute in France, in heavy weekend-return traffic with most of the cars for a mile or two ahead, looking like they might be braking. Or not. And since some cars have one rear fog light -- but others have two -- how's my depth perception? Is that one car up there a mile ahead? Or is it two cars near each other, each with one fog light?