On Monday, Volvo announced that it has teamed up with Swedish energy giant Vattenfall to introduce plug-in hybrid models to the market in 2012. But before we see the final production cars arriving in showrooms, Volvo will present a trio of V70 diesel plug-in hybrid demonstrator cars this summer to test the new technology. Click through to watch the video that includes interviews with several Volvo officials as well as footage of the demo V70 plug-in hybrid in action.