Point for Wendax.
Moved to the solved section.
I think it'll remain a mistery.
Not quite. I can't believe there was more than one Kaiser-based single-seater in Sweden, and I've just come across the entry and results for the III Skarpnacksloppet run on 13.9.53, roughly to the then-current Formula 1 regulations (the WDC that year was for F2 cars).
There is an entry by Arne Lindberg of a Kaiser-powered special, amongst the usual local Ford V8 specials. His entry number was #21, which means it's not the race covered by the puzzle picture, and he finished 4th overall, behind 2 Ford specials and a Cooper-JAP. I believe that the puzzle photo would have been taken at a similar event around that time, since most major Scandinavian races were held to this formula.
So i reckon we've identified the driver, at least.