As you browse the government auction sites above, you'll notice some link you to additional sites run by private contractors. These contractors have legitimate relationships with the government, but bidder beware: other private companies will try to make their auctions seem like government auctions as a marketing ploy. Always start with the legitimate links provided by the government itself. Good luck!
... The two auctions differ in terms of payment: In the pay-as-bid auction, bidders pay their actual bids. In the uniform-price auction, bidders pay the market-clearing price for all units won. 2 This paper compares these two commonly 1 In the Omnibus Budget Reconciliation Act of 1993, which authorized spectrum auctions, the U.S. Congress established the " efficient and intensive use of the electromagnetic spectrum " as a primary objective of U.S spectrum auctions (47 U.S.C. ┬ž 309(j)(3)(D)). 2 The cross-country study on Treasury practices by Brenner,Galai and Sade (2009)reports that, out of the 48 countries surveyed, 24 use a pay-as-bid auction to finance public debt, 9 use a uniform-price auction, and 9 employ both auction formats, depending on the type of security being issued; the remaining 6 use a different mechanism. In the United States, the Treasury has been using the pay-as-bid auction to sell Treasury bills since 1929 and to issue notes and bonds since the 1970s. ...
You can find some information online, on government websites which will let you search your area for a particular vehicle. These sites are not limited to cars, either. You can find SUVs, trucks and motorcycles on many of them too. Doing a ZIP code search and choosing a specific model will show you all the vehicles within a certain distance from you. Police specific auctions can be found by other websites like gov-auctions, which tells you when and where the local auctions will take place.
Consignee and consignor - as pertaining to auctions, the consignor (also called the seller, and in some contexts the vendor) is the person owning the item to be auctioned or the owner's representative,[65] while the consignee is the auction house. The consignor maintains title until such time that an item is purchased by a bidder and the bidder pays the auction house.
CWS Asset Management and Sales (CWSAMS) is a nationwide company with expertise in the management, marketing and sales of a wide range of assets, specializing in web-based and live auctions. CWSAMS has provided continuous support to the U.S. Department of the Treasury, its legacy agencies, and other public & private entities for the marketing and sale of real and personal property for the past 26 years. An abbreviated list of clients are: 

Age and nationality requirements. A bidding individual must be at least 18 years old to participate in government car sales. Unlike private auctions, which sometimes require a license to bid, a government car auction is generally open to the public. No special license is needed. However, in order to transact business with the federal government, a social security number or tax identification number is needed. If purchasing the vehicle for a company, then a Power of Attorney certificate is required
At Capital Auto Auction, we buy, sell and accept donations of used vehicles of various kinds. Whether it's for cars, boats or fleets of vehicles, we make it our goal to work out arrangements that satisfy both buyers and sellers. Our live auctions take place in four locations: Manchester, New Hampshire; Philadelphia, Pennsylvania; Temple Hills, Maryland; and Washington, DC. Our online auctions make it possible for you to bid on cars from your computer or smartphone. Also, in addition to hosting weekly auctions, we accept vehicles on consignments, doing all the advertising and networking to help you get a car sold.
Whenever bidders at an auction are aware of the identity of the other bidders there is a risk that they will form a "ring" or "pool" and thus manipulate the auction result, a practice known as collusion. By agreeing to bid only against outsiders, never against members of the "ring", competition becomes weaker, which may dramatically affect the final price level. After the end of the official auction an unofficial auction may take place among the "ring" members. The difference in price between the two auctions could then be split among the members. This form of a ring was used as a central plot device in the opening episode of the 1979 British television series The House of Caradus, 'For Love or Money', uncovered by Helena Caradus on her return from Paris.