At least the car was surely raced in the USA.
The whole thing was American.
BMC stood for British Motor Car Distributors Ltd originally (later British Motor Car Company) and they were the San Francisco-based agent for a multitude of British makes. It was owned by Kjell Qvale (92 this year!) who of course later went on to own Jensen in the UK for a time.
The Singer part of the name referred to the chassis, which was a British Singer chassis (at that time Singer still made the Singer Roadster, although being absorbed into the Rootes Group - later Chrysler - and then produce only badge-engineered Hillmans.)
The car was made by BMC in San Francisco, who apparently made a handful of glass fibre-bodied sports cars.
The puzzle picture actually shows Qvale himself racing the car.
