March 2002 Volume 83 Number 3 "serving the protectors"
Motoring
By Jim Barnett

Truly the new breed

Toyota has released a hybrid electric car that overcomes all the problems of its predecessors. Large battery packs that restrict space, limited range and long periods of recharging are all non-issues with the new Prius.

Prius comes with a clean, quiet electric motor, plus the flexibility of an internal combustion engine. The concept is simple, but the technology is complex.

Twelve computers manage this conventional-looking, high-tech sedan. A 1.5-litre petrol engine assists the electric motor when additional power is required, and charges the car’s 274-volt battery system.

The environment-friendly Prius uses substantially less fuel and produces only 20 per cent of the harmful emissions of a similarly sized conventional car.

Its power and range are extremely flexible and, given the right conditions, Prius could travel more than 1,000km on its 50-litre petrol tank.

Only the “hybrid” badge on the boot lid suggests this car is different. A conventional interior serves as the backdrop to a futuristic dash layout, while under the bonnet things look rather complex.

The real surprise comes when one starts the engine. Turn the key and the petrol engine comes to life – without the cranking starter motor noise. Release the foot-operated service brake, select “D” with a strange-looking gear lever and you’re away. One drives off to little or no engine noise and, due to the intelligent continuously variable transmission (CVT), one doesn’t feel any gear changes.

So how does it work? The electric motor is always used to power the car, so it is possible to drive some distance with the petrol engine off. As the need for power increases, stored electricity in the battery diminishes more rapidly. Then, the computer starts the petrol engine and runs it at low revs to recharge the battery. Push the foot down hard and the petrol engine runs at higher revs to help the electric motor power the car – with some power diverted to recharging. When the car is stationary or decelerating, the computer will generally shut off the petrol engine.

A dashboard screen shows a diagram of the hybrid power system. This screen instantly shows which power source is being used, the condition of the battery and when the petrol engine is off. The battery is continually monitored and topped up to provide maximum power to the electric motor. Aside from not feeling any gear changes, this car is normal to drive – until it comes to braking.

When one applies the brakes, the rotation of the wheels recharges the battery through the electric motor, which now operates as a generator. This regenerative braking system – which requires less pedal pressure – acts on the front wheels and helps stop the car.

While it’s no sports car, Prius has adequate power to push its Corolla-sized body and five passengers around with ease. It is quiet, comfortable and silent most of the time. Suspension is well sorted and provides a smooth ride and confident cornering. It cruises easily on the highway and has enough in reserve for safe overtaking.

Its 1.5-litre Atkinson-cycle, twin-cam, all-alloy engine features variable valve timing and delivers 53kW of power at 4,500rpm. Engine revolutions are governed to 4,500rpm to save fuel and allow for smaller and lighter internal parts. Working in parallel is a high-output AC permanent magnet synchronous electric motor delivering 33kW and a massive 350Nm of torque from zero to 400rpm.

Prius is sensational at the petrol pump. Toyota quotes fuel economy of 4.6 litres/100km around town and 4.2 litres/100km on the highway.

A Police Journal test – mostly in the city and suburbs – included a drive through the Adelaide Hills with four adults on board and the air conditioner running. The trip computer showed an average of 5.7 litres/100km.

The exterior styling is a little bland, but the pleasant interior is roomy, functional and comfortable. Prius features:

• Dual airbags.

• ABS brakes.

• Power windows and mirrors.

• A six-disc CD audio system.

• Climate-control air conditioning.

The only option is a touch-screen DVD satellite navigation system. Despite the battery’s location – the boot – it is well hidden and still leaves plenty of boot space.

Compared to the only other such hybrid available in Australia – the two-door Honda Insight ($50,000) – Prius is competitively priced ($39,990). This truly is the first step toward a new breed of future cars.

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