The drivers reportedly transported illegal immigrants from the Mexican border to Los Angeles. Some were transported in vehicles with specially-made hiding compartments under the hood.
The defendants told investigators they thought the African-American drivers, said to be hired in South Los Angeles, would arouse less suspicion.
The drivers' inability to communicate with the immigrants also meant they had limited information about the broader smuggling scheme, officials said.
The drivers were paid between $300 and $800 for each of the dozens of people they transported from the border to Los Angeles each month in 2010.
The Associated Press contributed to this report.