Volvo C30 electric concept, 2010 Detroit Auto Show

Volvo C30 electric concept, 2010 Detroit Auto Show

Swedish carmaker Volvo now operates a test fleet of all-electric C30 hatchbacks, and it's also rolling out another experimental car, a V60 wagon with a diesel engine driving the front wheels, and an electric motor powering the rear.

The two cars are now spawning a second generation of test vehicles, which take Volvo into the world of "series hybrids" or extended-range electric vehicles. They are being developed with a $1.7-million grant from the Swedish government.

One is a series hybrid--just like the 2011 Chevy Volt--that powers its wheels with an electric motor, but carries an engine that powers a generator to supply electricity to that motor once the car's battery pack is depleted.

Volvo will, in fact, experiment with three different layouts for range-extended electric vehicles, two adapted from the C30 Electric design and a third in a modified V60 Plug-In Hybrid wagon. Today the company released details of its three alternative designs.

First, put the engine in the other end ...

While the Chevrolet Volt has both its range-extender engine/generator under the hood up front, along with the electric drive motor, a small combustion engine can be put anywhere.

Volvo will test two C30 Electric cars, each modified to add a small, three-cylinder range-extending engine under the rear load deck. It's a surprising choice, since it's the opposite end of the car from the conventional gasoline C30, which has a front engine powering the front wheels.

Both variations have smaller lithium-ion battery packs than the all-electric C30, to make room for a 40-liter (10.5-gallon) gasoline tank and the engine.

Testing series hybrid ...

Volvo series hybrid (range-extended electric car) test vehicle layout

Volvo series hybrid (range-extended electric car) test vehicle layout

In the first design, the three-cylinder engine produces 60 horsepower and generates current that flows to the 82-kilowatt (111-hp) electric drive motor up front that powers the wheels.

The driver can also choose to direct the engine to divert some of the current to recharging the battery pack. This is a classic series hybrid design, where the engine never mechanically power the wheels.

The smaller battery pack in this variant provides roughly 70 miles (111 km) of electric range. When the engine switches on, it provides up to a further 620 miles of range.

... and parallel too

Volvo series hybrid (range-extended electric car) test vehicle layout

Volvo series hybrid (range-extended electric car) test vehicle layout

For the second test car, however, a more powerful 190-hp three-cylinder powers the rear wheels directly, through a six-speed automatic transmission.

It supplements the same 82-kW motor in the front, in an unusual design known as a "through-the-road hybrid," where both drive methods operate in parallel.

The engine can also be directed to provide current to recharge the pack or power the front electric motor directly. This one's the hot rod of the bunch, with more than 300 horsepower combined and 0-to-62-mph acceleration of less than 6 seconds.

To fit the engine and transmission in the rear, the pack size is reduced even further. It gives up to 47 miles (75 km) of electric range, again with up to 620 more miles from the engine.

Take 3: Classic plug-in hybrid

2012 Volvo V60 PHEV

2012 Volvo V60 PHEV

Volvo's third range-extended test vehicle forgoes the compact C30 hatchback. It will be built by adapting the company's design for its test fleet of Volvo V60 Plug-In Hybrid wagons.

That car is a "through-the-road hybrid," which can run solely on the diesel engine that powers the front wheels, on batteries alone through an electric motor in the rear, or using both powertrains together.

The newly-announced range-extended V60 test vehicle dispenses with that design. Instead, the entire package of 190-hp three-cylinder engine, generator, two-speed transmission, and 82-kW (111-hp) electric drive motor is mounted up front under the hood.

Volvo series hybrid (range-extended electric car) test vehicle layout

Volvo series hybrid (range-extended electric car) test vehicle layout

Up to 31 mph, the car is powered only by electricity, with an electric range of up to 30 miles. After that, the small gasoline engine kicks in to power the front wheels and recharge the battery pack.

This makes the test car very similar to the 2012 Toyota Prius Plug-In Hybrid that will launch in the U.S. within the next year.

Volvo said last month that a modified version of the V60 Plug-In Hybrid will be tested in the U.S. once Volvo adapts it to use a gasoline engine instead.

We can't help but wonder whether the range-extended V60 wagon is the car they'll test.



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