The car safety belt was invented by Volvo, but either they didn't patent it, or patented it but allowed other car makers to use it at little or no cost. I don't have a source, but I've read something along those lines online.
While Volvo didn't invent the first car safety belt, they invented the 3 point safety belt that everybody uses today. Lap belts would help keep you in the car, but the addition of a sash belt kept your face off the 50's era steel dash, and made seatbelts worth using.
Volvo patented it in the 50's and made it freely available for use.
