Detroit show: Prius powers up

THE latest version of the Toyota Prius – the car that means “hybrid” to much of the world’s population – was introduced to an eager media at the North American International Auto Show in Detroit this week.

Toyota’s third-generation petrol-electric car, which will go on sale in Australia in the third quarter of this year, is claimed to be about 10 per cent more economical than before despite being more powerful.

It retains the overall appearance of the current model, but features harder styling lines, a more Toyota-like grille and a slightly more rearward curve of the roofline.

Toyota claims that the new Prius has the cleanest aerodynamic profile of any mass-produced car in the world.

It claims to have devoted more time to wind tunnel testing than with any other Toyota in history, resulting in a drag coefficient of just 0.25Cd – down from 0.26Cd for the old car – with the main gains coming from the underbody panels, wheelhouse liners and the shape of the wheels.

Although it sits on the same wheelbase, the new body (with aluminium bonnet and boot) is slightly bigger, being 15mm longer and 20mm wider. This has helped to expand the cargo area while a new space-saving front seat design provides more rear legroom.

The new Prius is powered by a bigger 1.8-litre Atkinson-cycle four-cylinder engine that produces 73kW of power at 5200rpm and 142Nm of torque at 4000rpm – up from 57kW at 5000rpm and 115Nm at 4000rpm for the existing 1.5-litre version of the petrol engine. And the electric motor now has 60kW, up from 50kW.

This improves performance enormously, slashing the 0-100km/h acceleration time from more than 11.0 seconds for the old car (for which no official time was released) to about 10.0 seconds.

As well as improving performance, the more powerful engine enables the new Prius to run lower gearing so it cruises at lower revs on the highway, resulting in better fuel consumption.

Company officials in Detroit said that, while the current Prius averages 46 miles per gallon (5.1L/100km) on the US EPA’s combined test, the goal for the new model is a figure of 50mpg (4.7L/100km).

Toyota has retained a nickel-metal hydride (NiMH) battery pack in the name of cost and proven reliability rather than wait for the new lithium-ion (Li-ion) batteries that will appear in many electric cars from 2010 – including an expected plug-in version of the Prius.

It says the latest Hybrid Synergy Drive system is 90 per cent newly developed, with significant improvements over previous models. Together, the inverter, motor and transaxle are smaller and 20 per cent lighter.

One of the more interesting developments applied to the new Prius is an optional sliding glass moonroof that incorporates solar panels located over the rear seating area that are used to power a new ventilation system.

Not seen on a production car since being introduced on the ‘Jaguar-look’ Mazda 929 of the early 1990s, the solar-powered ventilation system uses an electric motor to exhaust hot air from the car while it is parked.

As well as being more comfortable for the occupants when they return to their parked car, it also reduces the work required of the air-conditioning system to cool the car. The system can also be operated remotely, so the driver can adjust the interior temperature for comfort before getting in the car.

Toyota has revised the whole air-conditioning system, a major energy drain, to increase efficiency and cool-down performance.

In addition, an exhaust heat recirculation system reduces heat waste by warming the engine coolant during cold start-up, for improved performance, and heating the passenger cabin more efficiently.

Another feature of the new Prius is the availability of LED (light emitting diode) low-beam headlights and tail-lights as well as stop lamps.

The car’s suspension is essentially the same as the previous model, but the brakes now feature discs all-round (ditching the existing rear drums).

Optional systems include radar-based active cruise control system with lane-keep assist, a pre-collision system that retracts the seatbelts and applies the brakes when a crash is deemed unavoidable and a revised automatic parking system.

The first-generation Prius entered the global market in 1997 as the world’s first mass-produced hybrid, but did not come to Australia until 2001.

The second-generation model came here in 2003 and last year Toyota Australia sold 3413 examples – more than the number of cars sold in 2008 by 25 individual brands, including Alfa Romeo, Chrysler, Citroen, Fiat, Mini, Renault and Saab.

As Toyota Australia boss David Buttner pointed out, for every Hummer sold, three Prius were purchased.

More than one million Prius have been sold globally, with most going to the US. However, the global recession has put on hold plans to start producing the car in the US later this year.

Toyota says its engineers developed the third-generation Prius by combining a refinement of existing systems with “an aggressive measure of new technology necessary for the future of automobiles”.

The company said it will be built using processes that reduce pollution in every stage of vehicle life, from production and driving, through to disposal.

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