Just for documentation in the hope this is later discussed and analyzed, where there is time:
Note that you use car models as a case where there is no problem. I used the same example previously as an example of problems... :-)
One Wikipedia has one article per car model revision (making it easy to store data on it), another on article per model name (with different data for the various runs, like 2000-2006, 2006-current). Almost always the data about the revisions will differ. But how much? If any feature is different, weight must differ, but it will even differ for customization, so it is probably necessary to ignore this and subsume it under a higher class. Is different length also irrelevant? Similarly: Models in different country that are sold under different names may be are sufficiently identical or not.
This will come out if we store data on the entities, whereas it is irrelevant for the present interlanguage links. The community will have to make decisions, and the Wikidata structural and user interaction model will have to support forth and back changes while a community discussion process if ongoing. The reason I ask for an analysis of the options (I gave three) is that this must be supported by wikidata.