You’re buying a used car, it’s not new, so you have to expect some wear-and-tear issues. The older the car, the greater the wear-and-tear, and the more likely it is to have suffered mechanical failures or even a crash. That means you have to thoroughly check the car before purchase, and you have to rely on the honesty of the vendor. If the car has had clutch problems it should be recorded in the service book. It’s the same with the others you’re looking at, check them thoroughly, and if you’re uncertain have an expert check them for you. Of the three others you are considering I would avoid the Passat as a potential money pit, and go for the i40 in preference to the Commodore.