Currently you would tag a question about 2003 Honda Civics by using the honda and civic tags. Would it make sense to make more specific tags like 2003-honda-civic and 2005-honda-civic which are both synonyms for seventh-generation-honda-civic (https://en.wikipedia.org/wiki/Honda_Civic_%28seventh_generation%29)? Then we could subscribe to questions that affect cars we own or have experience with.
I'm with Bob here, I think more general tags are better. In the case of the example you give, a question about a 7th gen Civics might be something that is easy to answer for someone who owns an Accord, as there are parts in common between different models in a range, so the Honda tag would attract them, wheras a specific tag would not.
Personally, I'd rather have several inclusive tags rather than a single exclusive tag. Example: the 2002 WRX (in the US) and the 2004 WRX models have many points that are similar (e.g., the engine, turbo, etc.) and other points that are different (e.g., the headlights). I have a 2004 but could probably provide someone with useful advice about their 2002. If nothing else, I'm closer to their ballpark than a non-WRX person.
EDIT much later because I don't think I was clear: a single "wrx" or "civic" tag is potentially more useful than a "2004-wrx-wagon" tag.
Some questions really are specific to a particular model in a particular year or range of years. I don't think there is a consensus yet on how to tag such questions.
General questions should use general tags, sure.
Somebody asking a question about a 2003 Honda Civic quite possibly does not know how much a Civic has in common with different Honda models of a similar vintage, though. Let them ask their question and take their best guess at tagging it, and if it really is a more general question, somebody who knows better can retag the question.