These cars came out circa 1979 and were originally sold by MDC/Roundhouse. The first releases used Atlas trucks with silver metal wheels. MDC discontinued the line for a while, only to re-release them in the mid-80's in kit form. I'm told that the trucks and wheels that came with the kits are terrible. Post-2000, MDC once again started selling these cars "ready to run". Circa 2005, Athearn acquired all the old MDC/Roundhouse cars and re-released some of them under their own label. However, I'm not sure that this particular car was ever run by Athearn. In addition to being available as singles, these cars are also sold in 4 and 12 car sets.
Although vaguely reminenscent of cars manufactured by PC&F, I'm told that this model is a complete foobie and not based on any actual prototype. FWIW, the painted-on build dates are generally from the 1970s.