Buy new no problem meh? My F10 has been veering to the left... now I see the suspension rear driver side is lower than rear passenger side... my E90 LCI brand new from PML also had weird engine issue and it felt very underpowered. Nobody could pinpoint where it went wrong. After several visits to PML and MA, I sold the car.
All heng sway one lah.
The big problem with used car is this... most of the time when we first buy a used car we are overzealous with the initial visit to the workshop. Like xiaofoggy... my first E90 was 2nd hand and I went to change so many things hoping to get it fixed "once and for all". No such thing. Car will slowly kaput one. I also spent around $8K on the E90 before I traded it up for a E90 LCI (now I feel cheap and stupid. don't ask me to exchange singpass pls).
I also subsequently bought a Volvo V50 second hand and made the same damn mistake by overspending on the initial repairs. The Volvo is still around, and it has been giving small issues every year. So that is something I really learnt the hard way.
My wife bought a used Mazda last year, and I did not get overzealous with the repairs. You must be thinking "Jap car what, won't pai one". You are WRONG. A lot of small problems, just that I didn't bother. And the car itself is crappy and noisy, so you do not really feel/hear it. The engine has a ticking noise, I think its the valve lifters. The suspension is creaking its ass off, I just turn up the radio. It's veering to the left, I did an alignment, no dice, fuck it, just drive it. It also has a persistent CEL caused by either bad O2 sensor or catalytic converter. I just ignored it. As long as it is not something major or affects safety, I just ignore it. To date the repair bills for the Mazda has been kept to a minimum, to an extent that I didn't bother to change the O2 sensor despite the CEL. I just bought a OBD cable from eBay and reset it before going inspection

Being cheap got art one, OK? don't ask me to exchange singpass pls