Earlier quoted context omitted.
Of course, because DDG can't build a profile of you, it would have to resort to some guessing. For example, if you search for "python", it would have to guess whether you are a programmer, or a biologist, in order to present the most relevant results. And of course, Google already has all this information...
...not that kind of guessing. Obviously. That's not "similar to the search query", that's just different meanings of words/phrases. I didn't say anything about that, but it looks like you didn't read past the first sentence anyway. Example of what I meant: https://duckduckgo.com/?q=BMW+723i
Seriously, quoting that is a reasonable solution. Given the comparative popularity of the two, it seems statistically likely that most people actually wanted a 323i. Having said that, I note that Google doesn't show 323i results for 723i, so... hm.
I do think explaining the substitution that was done and linking to the exact search (ie, how Google does it) would be a good feature though.