1 URL - Multiple Keywords: how much is too much

How many keywords can you target one URL with?

During my own experience, I've successfully targeted 1 URL with 2 keywords. I'm wondering if there's a limit before all of the backlinking become less effective.

As an example I'll use used cars in Texas.
I've ranked for keyword combinations similar to "used cars texas" and "texas used cars". I'd like to know if I can also start ranking for keywords like "best used cars texas", "used car lot texas", "affordable used cars texas", etc.

I know the standard answer here is to target each long tail keyword with it's own article, but for some low volume keywords that might not be economically feasible. Also, I think it's just good information I'd like to know.

Let me know if anyone has any real experience building backlinks with multiple keywords to 1 article/URL.

You can still do more long tails but make sure to include them in the page content not only the backlink anchor.

My experience is that anything over 4 keywords is a bit excessive.
Not because its bad or anything but people are lazy usually.
They won't type over a specific amount of keywords when searching.
There is also the possibility of less matches with all the keywords.
But then again you can target a large group more since you have more keywords.