From my tinkering, I've found that MJPEG streams are the lowest latency live video I can get. Old school, but no buffering like HLS or MPEG-DASH, etc. I haven't tried modifying the buffering in HLS and the like to zilch (or at least as low as I can go), but that's one thing worth exploring. I keep it low res (640 x 360) and low fps, but use the new high quality Raspberry Pi cameras to get an image that looks decent regardless.

One way to get around the latency issue with RC cars is to pre-plot the path and build a puzzle around that. (Not that there has to be a puzzle in there.)

Also, if you like scale models, have we got somethin' cookin' for you!