Could it be? Could Cadillac be working on an even higher-end version of its ELR plug-in hybrid? Well, General Motors' Executive Vice President Mark Reuss has gone on record as... well, not saying much. The exec was more than a bit coy on video (which you can view below) when asked about the idea of an ELR-V, although he did say that Cadillac was looking at "expanding the tuning envelope" for its plug-in coupe. What that means could be hinted at in these spy photos.