https://en.wikipedia.org/wiki/Tetraethyllead#Phaseout_and_ban https://en.wikipedia.org/wiki/Tetraethyllead#Phaseout_and_ba... May be relevant to the discussion

https://en.wikipedia.org/wiki/Tetraethyllead#Phaseout_and_ban https://en.wikipedia.org/wiki/Tetraethyllead#Phaseout_and_ba... May be relevant to the discussion, probably more so considering cars going hybrid.