Test-drive – Toyota Prius

Test-drive – Toyota Prius

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I’m not sure if I like the looks of the Toyota Prius although it is described as a ‘futuristic style’ (the styling was done by Toyota’s studio in California). The nose, with a beak-like appearance, seems out of sync with the short rear end. But in aerodynamic terms, the bodywork (slightly longer than a Corolla) is class-average at 0.30 Cd. The compact body also makes for easy parking, with an impressive turning circle of 9.4 metres.

The suspension system gives a hint of the next generation of chassis layouts from Toyota with strut front and H-shaped torsion beam rear axle with toe-control links. You can see almost similar arrangements in some of the new Toyota models that have been introduced.

The dashboard area reminds me of the ones in concept cars. To maximise legroom, there is no centre section going down to the floor. The shifter for the automatic transmission is to the left of the steering column. It has an odd pistol-grip shape but proved easy enough to operate. The parking brake is foot-operated.

The instrument panel is absent from the area ahead of the steering wheel, which gave an awkward feeling. And no heads-up display is projected on the windscreen either. Instead, a narrow display screen showing the warning lights and speed is recessed in the centre of the dashboard just below windscreen.

I questioned a designer about this location and obviously, I was not the first because the engineer confidently said that I should try driving the Prius and see if I felt it wasn’t good. Later on, I had to tell him that it wasn’t as dangerous as I thought it would be, requiring the driver to look away from the road ahead. Cleverly, the designers had enlarged the size of the speed display so that it is clearer. The location is not on the periphery of the driver’s view either so it is noticeable. The legibility also has something to do with the distance of the display; studies had shown that older drivers could read the more distant display 25% faster than when it was near the steering wheel.

But while I had to retract my scepticism of the speedometer position, I have to say that the 150 mm-wide information panel in the middle of the dashboard should be less ‘informative’. It shows, among other things, the modes in operation and how the energy is flowing in real-time. For instance, on deceleration, you can see that energy is flowing backwards to the batteries.

It’s a nice idea for a prototype and for test purposes, but I feel that it is really very distracting for the driver. The designers may argue that the novelty of seeing the display would wear off after a while – but then again, he or she could very well crash at the first corner after the Toyota showroom!

The rest of the Prius cabin, which is spacious with the 2.55-metre wheelbase, is quite conventional. It is designed according to the company’s Global Outstanding Assessment (GOA) criteria so the inside areas are suitably padded to minimise injuries. The front seats also have a special design to lessen whiplash injuries.

In the past, prototypes never had air-conditioning as it was a technical issue that was hard to resolve since the compressor usually needs a running engine. In the Prius, with its auto cut-off for the engine, this too presented some problems. However, the engineers couldn’t omit an air-conditioner since buyers expect it as standard these days.

So what they did was to improve the system to heighten efficiency and also use UV-blocking green glass that significantly reduces the introduction of radiant heat. The bodywork insulation prevents heat gain within the cabin. And finally, there is a mode which cancels the engine cut-off feature so that the a.c. compressor can be kept running to provide cool air.

Still, one wonders about the comfort in tropical climates like Malaysia. Mr Okamoto said that they had not found any problems in this area although he admitted that because the engine may be running more often to keep the compressor operating, the fuel economy may be affected very slightly.

The same consideration was given to power steering–another power-robbing ancillary. In the Prius, the system is run by an electric motor (not a new idea) so whether the engine is running or not doesn’t matter.

It was a bit exciting getting to drive the Prius since there was so much hype about it. At rest, it was silent since the electric motor provides the initial propulsion. I applied a bit of pressure on the pedal and the car moved forward gently. Only tyre noise was audible as the petrol engine was not running (and I knew this from the display). Pressing harder, the power flow arrows showed that the engine had kicked in. But the electric motor had disengaged and when I pushed the pedal right to the floor, the electric motor started to run again. I got the Prius up to 100 km/h easily but the acceleration was not particularly inspiring. More impressive was the torque which permitted brisk acceleration on the move.

Deceleration was smooth and the display told me that energy was actually flowing backwards to recharge the batteries. In fact, each time I lifted off and coasted, the regenerative effect went into action. To see how fast the system could react, I coasted and then floored the pedal – the arrows switched direction almost instantly and there was no judder at all as both motor and engine cut in suddenly.

Coming to a quiet stop, I waited for the engine to cut off… but it had already done so earlier when I started braking! So stopping was really a matter of the car ceasing motion, that’s all.

In the handling department, the Prius felt like any other car and rode comfortably as well. I must say, though, that the ‘drive-by-wire’ concept is fine and doesn’t take away any of the feel a driver is used to. A Toyota engineer said they worked very hard to have just the right sort of feel and weighting to the steering and pedals as they were aware that the absence of such tactile cues would be detrimental.

If the Prius were to cost as much as a 1.6-litre petrol-engined car, it would probably be quite popular among those who want the best in fuel economy. Surveys showed that the initial group of buyers in Japan and the US were mostly academics who were curious about the technology and young people who had strong views about protecting the environment. This buyer profile should change eventually but the main thing for Toyota is to get as many people as possible to use cars with the hybrid system. Not just to make money (obviously they would want to profit as well) but to make a significant and positive impact on reducing pollution and conserving energy resources which are not unlimited.

Chips Yap

Related stories:
The Toyota Hybrid System

Singapore government gives incentives for cars like the Prius


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