Have prearranged agreements with dealers. Have limited dealer networks. Have severe limitations on their ability to work in different states and with different models. Probably won't sell you a Saturn for example. Are illegal in some states.
Brokers usually take possession of a vehicle first, then resell it to the end user.
Benefits due the consumer from the automaker do not automatically transfer. Buyers may not be protected by the Lemon Laws. Special benefits, like first-time buyer rebates, special lease programs and special hidden automaker promos may not come the buyers way. Commonly receive the factory or government recall notices, not the owner. May not work with trade-ins.