At one time in my misguided youth I use to model Era 2/3 German rail in HO . Lots of Roco , Rowa , Klien Model Bahn , and various other European model train companies rolling stock filled my shelves . Never really got a layout up and running though , but had lots of rolling stock . The are differences between UK and North American wheel sets , although there was some international trade from time to time ( but best to buy local , creates jobs and taxes ) .The Hantons car you posted has US style trucks , Also the UK did , have back in the 30-50s cars set up to European standards that could be ferried to and used on European track . But that's a long and convoluted tale for another time and a Model RR forum . Suffice to say the Sarissa car will "pass" for early US / UK usage , if you are not a model railroader , just like some of the resin 1/56 stuff out there , it will pass if your not a scale modeler . The Roco car you posted is an actual pre war ( 1930s ) 4 wheel flat . Some are still in use today ( new decks , brake up grades , etc ) , yes still in use today in the modern German Army , it was that good of a design . BUT the 4 wheel couldn't carry a Tiger , you needed a 6 wheel flat .