Scale
HO Scale vs 1/64th Scale
The above photo is an AFX car (the orange Javelin) and a Herpa HO model car. (Yellow '69 Mustang)
The AFX car is 1/64th scale, true HO scale is 1/87th scale which is exemplified with the Mustang. Many people misnomer these Slot Cars and refer to it as HO racing, but it's really 1/64th scale racing.
While I'd love to see high detailed 1/87th cars that run like tjets, making a solid easy to work on chassis that small would be quite challenging. As it is, most people seem to prefer the 1/32nd or 1/24th scale cars because of how much easier they are then the 1/64th scale cars to work on...