Why would you want to make it slower?
I don’t plan on ever living where EVs, at their current technological revision, are practical.
Chances are that old EVs with battery packs needing replacement will be available cheap in the future, and at the rate things are going, I don’t expect all the manufacturers to still be in business to support restoring them back to original function.
Maybe that revolution in batteries we’ve been hearing about for the last 40 years will happen in the meantime and that will change the calculus.