With its divorce from parent Ford Motor Company imminent, Volvo Cars is fast relearning how to develop its own technologies. Not that it ever lost its engineering skills; many safety technologies used across the Ford portfolio were pioneered by the Swedish firm.

Volvo's latest foray is an announcement that it will put plug-in hybrid electric vehicles on the market "as early as 2012." Notably, its entry could well be the world's very first plug-in diesel hybrid--though technical specifications thus far are sketchy.

The company's ultimate goal is a series hybrid like the 2011 Chevrolet Volt, which operates entirely as an electric car for its first 40 miles of range--unlike plug-in versions of cars like the 2010 Toyota Prius hybrid that switch frequently between electric and gasoline power.

The company says that over the NEDC standardized European driving cycle, its plug-in diesel hybrid will emit less than 50 grams of carbon dioxide per kilometer.

Considering that the very best European subcompacts, with optimized turbodiesel engines and lots of high-mileage tweaks, emit roughly 90 g/km, Volvo's claim of 50 g/km is impressive indeed.

The cost of the necessary lithium-ion battery pack, however, will initially skew the economics heavily toward the standard diesel option. Only Peugeot-Citroen has announced plans for a diesel hybrid, and that's not expected to be a plug-in, at least at first.

In Europe, Volvo's plug-in would qualify for a "super credit tax incentive band", and individual countries also seem likely to introduce their own tax incentives for ultra-low-emission vehicles. You have to admit, a "super credit tax incentive" just sounds impressive, no?

Volvo takes the usual line that charging the pack with grid power from renewable sources permits much lower life-cycle carbon emissions. That's true, but of course it all depends on how green your local grid is.. In this case, Swedish energy company Vattenfall will offer buyers an option to supply them only with renewable electricity from wind or hydro sources.

Volvo CEO Stephen Odell stresses that the company's future plug-in hybrid will be "a thoroughly enjoyable car packed with Volvo's renowned high safety and genuine driving pleasure." (In other words, not a nasty little golf cart as some US drivers seem to fear.)

Volvo and Vattenfall first announced their partnership in January 2007. That effort culminated with the ReCharge plug-in hybrid concept shown at the 2007 Frankfurt Motor Show.

This summer, three Volvo V70 demonstrators, converted to plug-in hybrids, will be tested by drivers to get real-world experience with how they are likely to be used. An additional challenge for Volvo will be the cold Scandinavian weather, as electric-car range falls at low temperatures.