The Throttler's Hot Rod Club held a picnic and 'time trials' in Woodland Hills.  Early on it was hot rods and track T's (covered elsewhere on this website).  This is later on maybe 1950. 

Another shot from the picnic. 

OK race geeks, how many of these cars can you identify with their drivers?  I wonder if it is Sandberg hill climb... 

It looks like another trailer behind the race car.  Also the seats are padded for all day riding comfort.  Probably Henry Manney's Cooper Formula 3.  So this could be a 'test and tune' day on Mulholland Drive.