Actually, I don't have to imagine it. I did it (sort of). When I was 4, my friend Annette ( ) and I took our "Big Wheels" (those were little plastic tricycles with petals on the front wheel) and drove them onto a 55 mph country road. I can't remember but I think we were trying to get to the local general store to buy candy.
Needless to say, our parents WERE frightened and made a Very. Big. Deal. of it after a friend of the family drove past us, stopped, and brought us home.
OMG!! Where the hell was his grandfather???? That's not my idea of responsible babysitting - holy crap! yet - the little one sure is a pretty good driver, negotiating around a couple of buses!!! yikes....