If you're not already familiar with the story of the Cadillac Converj, take this quick primer: the Converj is the Chevy Volt's luxurious, canceled cousin. The up-and-coming concept suffered an early death shortly after its debut at the 2009 Detroit auto show. Now it's back, returning to development under the name Cadillac ELR. The new electric caddy is said to feature an updated version of the Voltec powertrain, complete with a Chevy Volt-like range-extending generator. Detroit pr