This is a reply to fc1yrg comment: 

"I was looking for a used car but ended up buying a new car. I heard the following cons about used car:

1. Some used 4x4 have been driven in the dunes and rolled.
2. Re-fit of some safety features, i.e., air bags are v. expensive. Most used cars that have been in an accident where air bags have gone off, have not had their air bags re-fitted.
3. Most people sell their used car after they have been in an accident because the 'feel good factor' is not there anymore. There no way to know if the car has been repaired properly to 'standard'

I do not know to what extend these are true, so am not discouraging people from buying used cars , but for my own peace of mind, I decided to get a new car. "

Sometimes, we cannot really rely on buying used cars becuase we don't know the (real) reason why the seller is buying his/her car. But let's not  really generalize it.. Some might be selling their used car because they found something new... better than their old car... but the main point here.. If you wanna buy used car be sure to really check the inside and out... and its better if you personally know the seller to avoid scams