Car 331 survives today because it was sold to MGM Studios in 1940. It appeared in such movie classics as "Singin' in the Rain" before coming to the museum in 1966 along with sister car 332. Car 331 spent most of its PE career on local lines in Redlands, where it made the last trip on the Smiley Heights line in 1936. It was retired in 1941 following assignment to local lines in Pasadena.
The Birney Safety Car, named for its designer, was the street railway's first successful standardized car design. Developed in response to a need for economical equipment to use on lightly-patronized lines, the Birney could be operated by one man serving as both motorman and conductor. this was made practical by use of a number of patented safety features, including controls which were designed to automatically stop the car should the operator become incapacitated.
In addition to the significant savings in labor costs, the Birney's light weight also reduced wear on the track and offered substantial savings in power costs. The trade-off was that their spartan interiors and rough ride did little to attract new riders. Over 6,000 Birneys were ultimately built for service throughout the country. PE owned 69 Birneys.