>Compressing the air a la turbo or superchargers comes at a price.

Don't forget that a turbo IS a supercharger! just that it's driven by
exhaust gas flow rather than a belt or gears. When used in US bombers
during WW2 they were called turbosuperchargers, but this was later
shortened.

I read in an Australian car magazine some years ago that VW was
investigating electric superchargers, contracting Mitsubishi Electric to do
it, but have heard nothing since. The unit was based on torpedo-motor
technology. This is not humor, despite its being Friday here.