That's true; if we're going into chassis-code level detail identifying cars, there's going to be a lot we simply can't identify with the information we have access to.
I know BMW is relatively easy, their chassis codes identify one generation of one car. I think a few cars have different codes for wagon or convertible bodystyles, but that's not hard to spot.
On the other hand, there's manufacturers like Toyota, their chassis codes include both trim level and engine.
Even then, those two manufacturers have rather well known and documented chassis codes, most don't. I've never even heard of a Volvo code.
That said, I'm all for including them to whatever extent we're able.