Toyota Prius

Introduction

The Toyota Prius is one of the first mass-produced hybrid power cars. Toyota have successfully combined a 1·5 litre petrol engine with an electric motor and a whole bunch of batteries to produce something that has low emissions, low fuel consumption but respectable performance. The Prius does make some compromises compared to a more conventional car of its size but as I discover the car works very well.

Drivetrain

The Prius mates an electronically controlled continuously variable transmission with a 1·5 litre, direct petrol injection, variable valve timed four cylinder engine (phew!) electric motor / generator. The petrol engine produces 74 bhp and 82 foot pounds of torque and the electric motor produces 67 bhp and 295 foot pounds of torque. The car’s electronics use one or both of the engines for motion and all systems are electrically driven apart from the heater, which relies on engine coolant (although readers should note that the car also stores hot coolant and boosts heater output when cold, so as to reduce how much it depends on the petrol engine).

In simple terms, in the city the car relies more on the electric motor but on the motorway it uses the petrol engine more. Of course, things are rather more sophisticated than this but you get the idea.

The battery is recharged by the electric motor and by regenerative braking – when you push the brake pedal you engage the generator, which recycles energy that would otherwise be lost. If you’ve driven an earlier generation Prius, take note that those powered by the Hybrid Synergy Drive (2004 onwards) have an enhanced regenerative braking system.

Performance

The Prius’ performance is for the most part materially stronger than one would expect for a car of this size with a 1·5 litre petrol engine thanks to it using one or both engines depending on the particular circumstances. In the city it is also especially quiet, since it’s possible to drive around at up to somewhere close to twenty five miles per hour without using the petrol engine. This means you can creep up on people in car parks cough.

At a higher speeds the car accelerates materially quicker than one would expect. This is because of the cumulative effects of two engines, clean aerodynamics (the Prius has a very low Cd of 0·26) and the continuously variable transmission, which allows the engine to run at a high engine speed without the bother of changing ratios. The car is not particularly bothered by motorway gradients because it uses the electric motor (running on battery power) to provide additional power. However, should one manage to reduce the battery charge through a very long uphill climb, performance is markedly degraded. If one drives up the Grapevine just north of Los Angeles, four up and with plenty of luggage, you will drain the battery almost at the summit cough.

Official performance figures for the North American market are a maximum speed of 103 miles per hour and an acceleration time to 60 in 10·1 seconds.

Fuel Consumption

This is where the Prius has to do well, otherwise people won’t bother buying one.

And it does. The Prius offers fuel consumption close to that what we’d expect from something smaller, modern and diesel powered. On the motorway one can expect somewhere around fifty eight to sixty two miles per (UK) gallon if you’re prepared to drive in an economical way. In the city, at least the same - in practice the car will often use less fuel in stop / start traffic because the petrol engine is not used much and it relies on battery power.

Equipment

Toyota have given the Prius plenty of equipment even in base level. The particular model I was driving had a lot of gadgets and toys. Cruise control, ABS, climate control, electric windows and mirrors. It didn’t have a leather interior nor adaptive cruise control but it did have voice command (you talk to the car, it does what you say) and integrated satellite navigation. That’s how we found our way across California!

Interior

Although the Prius is relatively cramped when compared to something like a Ford Focus, it has enough space for a family plus luggage, although room in the boot is a little cramped thanks to the battery pack under the boot floor.

One key point of the Prius is how eerily quiet it is at highway (motorway) speeds. This is a by-product of efficient aerodynamics and relatively skinny tyres.

The Prius also has a splendid driver information centre that can be used to tell you all sorts of facts about the car, such as fuel consumption, energy usage, the ‘phone (hooked up via Bluetooth) and of course the navigation.

The Drive

With its green credentials, special slippery aerodynamics and even relatively narrow tyres on lightweight wheels, one could be mistaken for glossing over the way the Prius drives, but this would be to discredit Toyota’s efforts. It’s no sports car, but as I have already hinted at, it’s nothing like as sluggish as many machines with this fuel consumption are. The Prius isn’t like Vauxhall’s EuroIV emission Astra 1·7 DTi with its specially tuned ECU that doesn’t allow you to burn excess fuel, instead the Prius is as responsive as one would expect (if not more so).

The Prius feels “European,” it has a relatively firm ride with surprisingly reassuring body control in moderately twisty stuff (such as highway on-ramps), better than the older generation machine I’ve tried. Toyota tell me that there’s less weight at the back in the battery pack (now down to just 45 kg from something like 80 kg for the first Prius) but I think Toyota have simply sharpened the handling up and stiffened the chassis. I can’t comment on ultimate handling because the example I drove (a) wasn’t my car, (b) was in California and (c) wasn’t my car. What I can report is that with the relatively skinny tyres, grip isn’t outstanding.

Conclusion

I’ve only scratched the surface of the Prius’ ecological features. The car is packed with clever little features designed to reduce consumption. Of course, whilst geeky and tree-hugging these may be, it would be irrelevant if the car were dull to drive or just plain disappointing. But it’s not, the Prius drives as well as a conventional machine of the same size and brand.