Great fun and history, able to move amongst the cars in the paddock and they do hit it pretty hard. Been to the Pacific Raceways races that last 5 years in a row.
Their web site.....
http://www.sovren.org/
Allowed cars:
PRE-WAR - Automobiles produced on or before Dec. 31, 1940
VINTAGE - Automobiles produced after 12/31/40 and on or before 12/31/62 HISTORIC - Automobiles produced after 12/31/62 and on or before 12/31/69
and certain cars produced in the year 1970 that are a
continuing and unchanged series from 1969
Formula cars are as allowed by the Monoposto Register rules: thru 1963 for Formula Jr., pre-1970 for Formula V, Formula B, Formula C, and Formula II pre-1973 for Formula Ford, and thru 1966 for Formula 1.
At certain events, SOVREN allows an EXHIBITION class for distinctive racing automobiles which are too new to fit in the above categories but were produced before Dec 31, 1979 such as Formula 1, CanAm, TransAm, Indy cars, etc.