Laura, don't worry : when I saw the swastika on the car for the first time I knew that it wasn't disturbing in 1914-1918... WWII, Nazism and Hitler really interest me so I perfectly knew this but nevertheless as a XXIst century French student it's disturbing, now the symbol is disturbing because most of us thinks about Nazism when we see it. I'm not saying it's good or bad but it's clear that Nazism has a stronger impact than an old superstition about success and luck.
I also noticed that in French we make the difference between the religious symbol (called "svastika" in French and which is the equivalent of swastika in English) and the Nazi symbol (called "croix gammée" in French but in English there is no equivalent, it's swastika again even if the meaning of these 2 symbols are completely different !). So, in fact, the sign on this car is a "svastika" and not a "croix gammée".