When I was younger, a local home/car audio/video shop used to have clearance sales every Saturday morning (and I really mean clearance... this was the last stop before being thrown in the trash, and while there was plenty of junk occasionally a good but discontinued product would be found for a steal... but I digress). I remember finding a pair of Bose drivers... somewhere around 4" or maybe 5.25" as I recall... that I was told were car audio drivers. Who knows. I also remember them having markings on them of some crazy low impedance, less than 1ohm I think. Seems like it was 1/2 ohm maybe. I figure they were part of some dismantled factory system where several drivers were connected in series.