It's definitely a GM product, Ford, Mercury, Packard, Chrysler, Dodge, and Plymouth all have different lines and rear view mirrors. What does match is Buick and Chevrolet. Pontiac and Oldsmobile share a totally different squared off roof line. What is baffling is the dashes coming off the grill, that wasn't a feature on either Buick or Chevy. Makes me wonder if this may not be a Canada specific model which were typically based on US models with minor feature changes like a different grill.