Modern turbodiesel powertrains already match gasoline-electric hybrids in fuel-economy and often outmatches them when it comes to driveability and performance, but a combination of the two separate technologies could provide a perfect blend of performance and economy.

The idea of a diesel-electric hybrid is nothing new. Several automakers, such as France’s PSA Peugeot-Citroen and Mercedes-Benz, have revealed plans for diesel-electric hybrids, and now General Motors has joined the fray.

The American auto giant is reportedly working on developing a range of diesel-electric hybrid powertrains that could be in production within the next five years.

Development work is taking place at GM’s European powertrain division in Turin, Italy. Engineers are looking at everything from mild hybrid systems to more advanced ones, including a plug-in hybrid diesel based on the Voltec powertrain destined for the 2011 Chevrolet Volt.

Initial prototypes being tested are based on compact four-cylinder diesel engines and the first likely models to receive the ultra-efficient powertrains are the Opel Astra and Insignia (pictured).

The diesel hybrid makes sense as the electric component is ideal for inner-city driving while the diesel internal combustion engine is most efficient during highway driving. The biggest hurdle at the moment is cost. GM is targeting a cost premium of about $1,500 over a gasoline hybrid for its first diesel hybrid.

[Autocar]