Just to throw in my $0.02, here's my experience/guess about fuel filler door side...
Right hand (passenger) side:
-Older American car designs (Crown Victoria, Taurus)
-European market designed cars (the German brands, GM: G6, mailbu - derivatives of the Opel/Vauxhall Vectra)
I think putting the fuel filler door on this side is due to most fuel stations in Europe being full-service (at least the parts I've visited) and it used to be that way in this country (still is in New Jersey!)
Left hand (driver) side:
-Newer American cars
-Asian cars designed for US market