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First drive: Subaru EV ‘one cent a km’

Connected: The Subaru Plug-in Stella has a range of 80km in city traffic.

Aussie test run for nippy Subaru Plug-in Stella prototype

24 Feb 2009

SUBARU has unveiled an electric vehicle prototype that can cover 80km of stop-start driving for less than one cent a kilometre when re-charged with off-peak electricity – one tenth the running cost of a 2.0-litre petrol Subaru Impreza R.

Based on one of Subaru’s big-selling Japan-only kei cars, the Plug-in Stella electric vehicle will go into limited production later this year so a major Japanese fleet can assess the technology.

However, the latest lithium-ion batteries mean the plug-in Stella would cost more than three times its petrol-powered equivalent in the showroom if it went into production now.

Unveiling the car in Melbourne ahead of its appearance at the Melbourne International Motor Show, Subaru senior engineer Takashi Suzuki said: “We can only sell to municipal authorities and fleets – organisations that are concerned about reducing carbon dioxide emissions.”

2 center imageThe Stella is a neat little package, with ample headroom that is characteristic of upright kei cars.

Passenger space has not been impaired by the batteries, and four adults can easily be accommodated without squeezing, although people with small feet would be more comfortable in the back.

The standard Stella’s little 658cc, 40kW petrol four cylinder engine has been replaced by a 40kW electric motor and 16 battery packs arranged in three groups, four under each front seat and eight under the back seat.

The transformation adds a hefty 200kg to the Stella’s mass, lifting it to a considerable 1060kg.

This does not, however, detract from the Stella’s ability to nip around town, thanks to the torque-heavy nature of electric motors. The unit under the Stella’s bonnet punches out 150Nm, more than double the 63Nm of the standard model.

Even with four burly blokes on board, the Stella didn’t feel strained in Melbourne traffic as Subaru ferried us to the Port Melbourne go-kart track (we were unable to drive it ourselves on Victorian roads because the Stella does not have ADR type approval).

On the go-kart track, where we could have a drive, the Stella impressed with the surge of torque from low speed or even no speed, with that seamless acceleration that only an electric car can deliver.

Our car was specially kitted inside and out, as it was first used in public at the July G8 meeting in Hokkaido, where it ferried bureacrats and officials between venues.

It is impossible to know how much difference the special little alloy wheels and tyres made to the handling, but there was a distinct flavour of pram when push came to shove in the tighter corners.

But the Stella is not a sports car and handling should not be at the top of the assessment list.

On the road, the absence of engine noise highlighted the road noise, but this was kept at commendably low levels considering the body’s frugal use of materials and sound deadening. We never got above 80km/h, so wind noise was never a factor.

Mr Suzuki said Subaru had made significant strides in the 11 years it had been working on electric cars, and this was reflected in the Stella’s performance on the road and in the garage.

The 80km range is right up there for all-electric cars, especially a four-seater, and compares well with 64km for the Chevrolet Volt.

Mr Suzuki said the 80km range was based on a driving cycle with lots of stop-start driving, with regenerative braking helping to eke out the on-board electricity.

He said the Stella had a range of more than 100km when travelling at a steady speed on a highway because, while there was no regeneration going on, neither was there the need to accelerate constantly, which is a big drain on power.

Subaru has also devised a clever two-stage form of regeneration. In the L drive mode, the Stella applies maximum effort to regeneration when the driver uses the brakes, or even when they just lift off.

It is possible to drive around town without touching the brake pedal, using the retardation caused by the battery regeneration.

In the D drive mode, less retardation is evident when the driver lifts off, and the Stella coasts like a petrol-engined car in neutral. This prevents an unnecessary loss of speed when the driver lifts off.

Mr Suzuki said the Stella’s lithium-ion batteries could be recharged from a household plug overnight.

On Australia’s 240 volt system, a complete charge takes four hours. Based on current off-peak electricity prices, that would cost about 93 cents for every 100km. Even if you recharged during the peak, it would cost $1.88 to run for 100km.

That still compares well with the $9.24 it would cost to run an Impreza R for 100 km. Clearly, the Stella’s advantage would increase as world oil prices rise.

The Stella loses out in purchase price. Mr Suzuki said the lithium-ion batteries were expensive and would comprise more than 60 per cent of the Stella’s theoretical selling price of more than $45,000.

He said the petrol Stella would cost about $15,000 in Australia, but added that the batteries were still in low volume production and cost would come down dramatically as volume was ramped up.

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