The days when yellow-stickered partial-hybrid vehicles were allowed to travel with a single passenger on designated HOV areas of California state highways are over. As of July 1, yellow-sticker vehicles must meet a higher passenger quota to gain access to these highly coveted driving zones. Luckily, super-ultralow-emission vehicles, such as the natural-gas-powered Honda Civic, get a different white-colored sticker. And, all cars, including the Honda NGV, will continue to have single-passenger access to HOV areas…