We find that cars are quite indispensable property for us.  It is a matter of prestige for many, and they acquire cars as many as possible and keep them as a style statement.  For this, they even opt for pre used vehicles.  The best place to visit and purchase used cars is General Services Administration.  The GSA put up vehicles for auction and is a federal agency.  They get the supply of cars for auction through IRS, DEA,FBI or police departments, all government agencies.  The vehicles might have been taken into custody through seizures. Since the authorities are not interested in maintaining the possession of such cars, due to their high maintenance cost,  they sell these cars at very low prices.

Why do the government need to sell off its vehicles? Due to the frequently changing policies or due to a financial crisis or even a change in technology are these vehicles sold off.  By selling these vehicles to the general public,  the government writes off these vehicles from the book.   Since the government is constituted of many departments and further sections, the source of cars for sale are many.  Just to have an idea, take a look at a few  government departments.  They include the State and Federal governments, Fire and emergency services, Police department, Universities, etc.  A lot of cars come through these sources.  

In the US, the Government and Police department auctions are considered genuine.  
 
The financial institutions seize a good number of more or less new cars on a daily basis, for the reason of not paying the car mortgage value or other payments that were due.  The authorities sell off these cars in a jiffy, because the cost towards maintaining these cars would be over and above the amount they might gain.  Hence, these auctions are the best place to purchase  practically  new cars at cheapest rates.  Many used car dealers make a good business in this field .
 
If you are a member of an organization that has enough information and access rights to these auctions, you could participate in these auctions.  Thus they end up buying a  fairly new car saving a huge sum.  Purchasing a car through GSA is quite stress free, compared to other auctions.

Before attending an auction by a government department to purchase a car at a low rate, be sure that you have made  first round inspections done to your satisfaction.