The new McLaren Elva supercar costs $1.7 million, not including options like a sound system or exposed carbon fiber body panels. One option you won't be able to get: A roof. The Elva isn't a convertible. It's an open-topped roadster, meaning it has, literally, zero roof of any kind. You can pay a little extra to get a windshield if you want. (It will be legally required to get one in some US states, McLaren said.) To help keep the wind out of your face, the Elva's Active Air Management System deploys when the car is driven at faster than suburban street speeds, roughly 25 miles per hour. The system directs air around ... (full story)