I would go to Dodge by default, but that's just because for me that make is more well known.

I'd say that number of units produced/sold is the most important: if there are 5 times more one model than the other, even if not precisely identifiable statistically there are more chance that it is the most sold model.

If sales figures were approximately the same, I do not know which one to pick.
How do people refer to such case in North-America? Is not of the name more common when referencing them? (other than "K-cars" for example)
Or we just pick one or the other by default, as long as we indicate it is "by default" it does not matter much I suppose...