You can buy used cars from several reputable sources depending on your location and preferences:

• Online Marketplaces in Germany :
  • mobile.de is Germany's largest vehicle marketplace where you can find a wide range of used cars, youngtimers, and classics

* AutoScout24 is a large pan-European online car market offering many used car options

* autohaus24 offers thousands of used and new cars with transparent pricing and multiple payment options across Germany

* DAT AUTOHUS is one of Europe's largest used car dealers with physical branches in Germany and a large selection of vehicles

* Carvago.com provides an online service to buy used cars across Europe with inspection, paperwork, and delivery included

• Dealerships vs Private Sellers :
  Buying from dealerships is generally more secure as cars are tested and serviced, and often come with warranties, but prices may be higher due to VAT

. Private sellers can offer better deals but require more caution and possibly a used car inspection.

• Other International Options :
  • Cars.com and Autotrader.com are popular platforms in the US for buying used cars with extensive listings and reviews

In summary, for used cars in Germany and Europe, start with mobile.de, AutoScout24, autohaus24, DAT AUTOHUS, or Carvago.com for a secure and wide selection. If you prefer private sellers, use these platforms to find listings but consider inspections before purchase