Opel’s Rocks-e is a departure from the carmaker’s usual passenger cars. It’s a boxy, compact two-seater that is fully electric – officially classified as a light motor vehicle. It’s a particularly promising area for the carmaker as it seeks to embrace a whole new target group. The vehicle is basically 2.41-metre cube on wheels, on sale for €7,990 ($8,864), making it less expensive than almost all the conventional small cars out there. That makes the Rocks-e one of the cheapest electric vehicles around, and it doesn’t cost more to lease than a monthly pass for the city bus according to the mark…