EVERYBODY HAS AN OPINION on whether New Yorkers should own cars. At the mere mention that I was thinking about ponying up the bucks to buy (or lease) four wheels of my own, a friend who lives upstate insisted that it would be too much of a pain, saying that if I live in the city, I should stick with public transportation - why subject myself to car payments and parking hassles? But, oh, the dream of a car. Of having a small space of my own in which I could be out in the world, blasting '80s music (sans headphones), without having to wait, wait, wait for a train, a bus, a this, a that. Of skedaddling from town at a moment's notice (if the traffic isn't too bad) without checking the Long Island Rail Road timetable. Plus, to be honest, sometimes I just get sick of rolling jugs of cat litter home in my grannyish shopping cart. Oh, for the chance to go to Target, to buy the giant tub of litter and an eight-pack of paper towels and be done with such shopping for a while! My dreams had been deferred for far too long. It was time for an experiment in big-city auto ownership. I borrowed three small cars - perfect for swooping into the smaller-than-they-appear parking spaces in my neighborhood - and a Segway Personal Transporter, capable of terrifying small dogs at 12.5 mph. Here's how they, and I, fared.