Let's play a game. What's wrong with this mini!

So this is 1 I test drove. Was $23,500 when I looked. 3 previous owners, started at 28k and down to just under 21. I know I dodged a bullet here but what was the bullet? This thing is priced so low and has been sitting for over 4 months.

I couldn't figure it out on a 45 minute test drive, can you?