Why 20 feet? Golf carts are much shorter/narrower than that: https://jsgolfcarts.com/blog/golf-cart-dimensions/ https://jsgolfcarts.com/blog/golf-cart-dimensio

Why 20 feet? Golf carts are much shorter/narrower than that: https://jsgolfcarts.com/blog/golf-cart-dimensions/ https://jsgolfcarts.com/blog/golf-cart-dimensions/ You could comfortably fit three of them on two lanes, and believe me people will do it. Italians generally drive smaller cars than other Europeans and that's what happens there on intersections. Actually, considering the dimensions, a fully packed four-seater has a smaller footprint than the equivalent bicycles - even Dutch ones. If you put everyone in two-seaters riding alone, then indeed you'll have 1/3 the density of bicycles, but that's the lower boundary! Personally I don't see the point of maximizing it any further than what golf carts achieve. Especially that they provide appropriate comfort and stability.