It's spring, and what could be more pleasant than putting the top down in a stylish European four-seat convertible? We got the chance to drive the 2011 Volvo C70 recently, rediscovering the joys (and smells) of open-air travel in the spring sunshine. The C70 is a bit of an oddball in the Volvo lineup, which is otherwise largely composed of sensible sedans and capacious crossovers. It's what the Europeans call a coupe-convertible, with a metal roof that folds into the trunk within 30 seconds when you want it to become a droptop. It's a remarkable process to watch, as a collection of electric...