Supercars -- once exclusively the stuff of high-speed racing circuits and billionaires -- are going mainstream. From Ford to Ferrari, major auto makers are introducing ultra-high-end vehicles that rewrite the rules on cost, speed, and sexy design. (snip) Blazing along with the pack is the Ariel Atom 2, the stripped-down soul of a supercar. Unlike its classmates, the Atom doesn't come with an intimidating sticker price or luxury trim. Heck, it doesn't even come with doors, a windshield, or windows. It's a lean engineering marvel that has stunned speed freaks, racing fans, and the automotive press. (snip) IMPRESSIVE LIST. The...