The Motor Press Guild is the largest organization of professional automotive journalists in the world. According to the MPG website:

The Los Angeles-based Motor Press Guild (MPG) is a non-profit professional association dedicated to promoting education and information exchange within the motoring press. Members include staff and freelance journalists, photographers, broadcasters and similar media professionals, as well as public-relations representatives from vehicle manufacturers, industry suppliers, aftermarket companies, consumer groups, governmental bodies and other motoring-related firms and organizations.
MPG currently has some 750 members, most of whom work in Southern California. However, MPG members are also based in other regions of the U.S., especially the Midwest and Northeast.

MPG hosts Track Days annually for its members.