How about a front wheel mounted drivetrain with the motors built into the wheel hubs?
That would effectively add 4wd to old cars and allow the onboard engine to work normally with an option for eboost/edrive with the only extreme modification being adding the battery and control modules.
That would effectively add 4wd to old cars and allow the onboard engine to work normally with an option for eboost/edrive with the only extreme modification being adding the battery and control modules.