National Public Radio: In a few months, GM plans to launch its most anticipated vehicle in ages: the Chevy Volt. After years of hype, the Volt will join Nissan’s Leaf as the nation’s first mass-market electric cars. The vehicles are dramatically different — and how consumers will respond, nobody knows. But everyone in the auto industry will be watching to see what works, what doesn’t — and if America’s automotive future is electric. The Chevy Volt When you drive the Chevy Volt, there’s a …