The average US car is 4,000 lbs and has one battery. Your race car is not comparable. You are correct about the energy density, but the battery is used for re

The average US car is 4,000 lbs and has one battery. Your race car is not comparable. You are correct about the energy density, but the battery is used for regen breaking, engine start/stop, hotel loads, and in the case of Kia an electric supercharger. Essentially it provides smooth-over power, but the bulk will still come from gasoline. Lithium is used in electric cars where they are the primary energy source. Lead carbon is only appropriate in micro to mild hybrids.