New Push Bike

I've been haunted by the idea of changing the normal push bikes into something better that requires less movement and sweat and at the same time that you can use any day of the year, not only when the weather allows it. My intial idea involes 4 wheels, half the width of a car, comfortable car seat and you can hang a jacket behind the seat. I'm still working on how to actually make it move. Maybe it's electric. Another idea that comes to mind is to use the same theory as wind-up cars. Suggestions?