This Audi plugin hybrid mentioned in the article has a gas engine for the front wheel drive and an electric motor for rear wheel drive.  Just the conversion idea that we discussed here awhile back in one of bio-d's articles I think.

Any front wheel drive car could have an electric motor/battery system adapted to the rear wheels.  It's a simpler system for conversion of an internal combustion vehicle.  

The tEsla could have it's battery made smaller and add a backup generator so it could compete in the plugin hybrid market.  Just as the EV-1 could have been saved by a similar conversion to hybrid.  It extends the range and allows a visit to a gas station, instead of a lengthy recharge, to get going again on longer trips.

Actually the Audi design would allow any maker of a front wheel drive vehicle to simply add on an optional rear battery/electric drive.  It would work even better for all wheel drives.

Mass production of standard motor/battery units would then be adapted to various models and makes.  One or two large manufacturers could supply all the auto makers with the battery electric units.

It would also give every converted front wheel drive all wheel drive.  Combining the SUV like traction feature with the plugin feature.  Saving gas in the worst gas guzzlers.  And wouldn't all those minivan moms want all wheel drive for safety too?  Yep.

This is a happy marketing coincidence.  Could Toyota's complex parallel/series hybrid system yield to a simple parallel drive system like the Audi has?  I think it might.

Then as batteries become faster charging and have more capacity with less weight, the gas engine could be made smaller and electric motor made more powerful in future models.  For less and less gasoline used and more and more, hopefully renewable kwh.

Eventually the gas engine could yield to a solid oxide fuel cell/turbine that is 60% efficient and runs on various fuels.