Sometimes, you have to go across the border to get the skinny on what's happening in the US. For example, did you know GM might be testing electric cars with batteries that have about three times the energy density of today's EV?

That's could be the case, since during the recent Automotive Parts Manufacturers' Association conference in Canada, The Windsor Star reporter Chris Vander Doelen spoke with J. Gary Smyth, General Motors' executive director of Global Research and Development. Smyth told Vander Doelen, "Today there are prototypes out there with 400 Watt-hours per kilogram."

We have to assume Smyth was talking about batteries made by Envia, which announced it had developed just such batteries last year (and sent along the nifty cartoon image you see above). GM invested $7 million in the company in 2011 and also made a separate licensing deal to use those advanced packs in its vehicles. While we don't know the details of what kinds of vehicles are being tested with the 400 wh/kg packs in – Smyth would not even mention the brand – but we have previously calculated that that kind of power could mean 300-mile EVs. And earlier estimates put the cost of such a car with Envia's technology at just $20,000, giving more heft to Smyth's statement to Vander Doelen that, "Innovation is exploding right now. The industry is in a period of rapid transformation."