There are a lot of options out there for an "in car" fire extinguisher. It would be nice to see what some of the cars are currently using and what was used back in the day.
The State's 68 A/S Camaro was equipped with the standard hand held fire extinguisher.
An interesting inspection sticker attached, dated 1973, by the San Francisco Region, SCCA.
Wanting an exceptional fire system in the car, I installed a Halon system. Not vintage, but I feel some exceptions are necessary when it comes to safety. The system has nozzles plumbed to the fuel cell area, under the hood, and of course the passenger compartment. The system is easily activated by hitting the big red button next to the driver.