Our test drive showed that Toyota’s hybrid car can deliver substantial fuel savings - providing drivers make the right kind of journeys

Toyota’s Prius is, famously, a hybrid car. This means it uses an electric motor as well as a petrol engine to get from A to B. In the Prius, both engine and motor are able to drive the front wheels, acting either separately or in concert to get the car moving. In theory, this combination allows the Prius driver to save money and reduce CO2 output, using less fuel for a given journey.

Hybrids can be efficient but this is not a given - fuel saving depends a lot on how and where they are driven, so buyers considering a Prius first need to take a dispassionate look at their motoring habits.

The Prius will offer the most benefit on journeys where there is plenty of speeding up and slowing down, or lots of opportunities for coasting. So if most of your motoring is in a congested city, or on country roads with tight bends, or in hilly country, the Prius will likely do much better than a conventional rival. If the majority of your driving is done at constant speed on the motorway, you might as well buy an ordinary car and not lug around a hybrid’s heavy batteries.

In our tests, we saw mostly inner-city crawls and medium-pace motorway driving, and achieved an average of 52 miles per gallon. This falls well short of the official combined-cycle figure of 65.7mpg, but is nonetheless at least 20 per cent better than most similarly-sized petrol-powered cars could hope for on the same route. Many diesel cars would equal or beat the Prius’s CO2 emissions, of course, but in the process would produce much dirtier exhaust gases, which can worsen other environmental problems.

Toyota offers the Prius in three different specifications in the UK, called T3, T4 and T Spirit, with on-the-road prices of £17,782, £18,582 and £20,682 respectively.

All three levels come relatively well equipped, with electronic climate control for example, while the T Spirit boasts a Bluetooth hands-free phone facility and voice-activated satellite navigation. All variants share the same official CO2 output figure of 104g/km. That puts the Prius in Band B under both the current grading system and next year’s expanded VED roster. A tax disc costs £15 at present, and will cost £20 under the 2009 rules. Company car tax is 10 per cent of purchase price in the 2008/2009 tax year. The Prius is exempt from the London Congestion Charge, and will continue to avoid the fee after the upcoming rule changes, in force from 27 October 2008.

In size terms the Prius slots between the Mondeo and Focus classes - offering about the same interior space as a Renault Scénic. However, the Prius’s nearest direct rival is the Honda Civic IMA hybrid, which is a four-door saloon rather than a hatchback. The Honda costs about the same, looks more anonymous, is slightly less spacious inside, and feels more conventional in use.

Toyota’s complicated hybrid components are covered by an eight-year warranty, which helps to prop up residual values. About 55 per cent of initial outlay on a Prius is retained after three years, which is much better than a Renault Scénic and only slightly worse than a Volkswagen Golf.

For the price the Prius offers good interior space and reasonable comfort, a quality feel to the interior, and some upmarket touches such as puddle-lights in the front doors and lined storage spaces. It is not especially luxurious even in T-Spirit guise, but it is comfortable. It is also not remotely sporty, with high-set seats and numb-feeling controls helping to keep the mind set firmly on fuel-saving rather than fast cornering.

So, what is the Prius like to drive?

In a word, odd. The gear-change, instruments and many of the minor controls operate in unconventional ways and are found in unexpected places. Optimistic guesswork was not sufficient to get the Prius moving, for example, and after a few futile minutes spent prodding buttons, we were forced to break open the owner’s handbook.

One culprit in our confusion was the electronic automatic transmission, accessed via a stubby knob on the dashboard. Rather than slotting firmly into a drive, reverse or neutral position, this lever simply has to be slid momentarily up, down or across. The requested gear will engage, with a visual reminder on the dashboard, and on release the knob will simply spring back. This action felt odd to begin with but we quickly adjusted.

We also got used to the foot-operated “handbrake”, which fortunately is not needed during hill-starts. Instead the car simply will not roll backwards on a hill unless the driver selects reverse.

Ventilation, audio, trip computer and sat-nav controls can be reached via a large, centrally mounted touch-screen. In our T Spirit test car, many functions could also be controlled using a well-designed set of buttons on the steering wheel, or through voice commands.

Our test car was fitted with an automated self-parking facility, which will guide the car into a suitable space selected using the touch-screen and a rear-facing camera. We liked the camera - it offers a clear rearward view day or night, overlaid with coloured guide-lines even when reversing manually. The self-parking process works well enough but is much too fiddly to bother with unless you are hopeless at parking, however.

In general the car’s computerised controls work effortlessly. Most drivers will remain unaware that the throttle and brakes, for example, are drive-by-wire. You press the pedals normally, but the car’s computers decide what to do with the engine, electric motor, energy regeneration and brakes, depending on how urgently you use your feet.

Drive is via a continuously variable transmission (CVT), meaning that engine revs and road speed are largely unrelated. Press the accelerator hard and the revs will quickly rise and stay at a high level until you ease off again, allowing the modest 1.5 litre, 76bhp engine to work at its peak output regardless of speed, assisted by the 67bhp electric motor of course.

At low speed and when setting off, the engine will often not run at all and the car will drive on electric power alone, to save fuel. Engine combustion also typically halts the moment you lift off the accelerator, unless the battery charge is low. Transitions between engine and electric power are largely unobtrusive but are slightly more noticeable than in Honda’s Civic hybrid, particularly at low speed or when the engine is cold.

To boost fuel economy Toyota has worked hard to pare weight and improve aerodynamics. That striking, slippery shape does bring consequences, however. The Prius’s rear windscreen is split with an almost horizontal upper part, affecting rearward visibility and rendering the rear wiper largely pointless. The front screen pillars, meanwhile, get in the way when approaching junctions or roundabouts, requiring extra caution and some pigeon-like head movements to maintain safety.

Despite these niggles we found the Prius likeable and easy to live with. It is smooth, quiet, refined and fast enough. The suspension coped well with London’s pot-holed and uneven tarmac, and traversing road-humps did not require slowing to a crawl.

Urban buyers looking for an upmarket, safe and spacious five-door with excellent fuel economy should definitely test drive a Prius before making their purchase.

So, how does a hybrid Prius work?

It’s perfectly possible to run a Prius and cut fuel consumption without ever thinking about the hybrid mechanicals. But it can help to improve mpg if you understand what’s going on underneath, which is why the Prius’s central screen can show a real-time diagram of how energy is transferred from engine to wheels, or wheels to battery, or battery to motor.

The electric motor draws its power from a large battery pack mounted between the rear wheels, and all of the power for that battery comes via the petrol engine - you never plug the Prius into the mains to recharge. Instead the batteries are charged directly by the engine, just as an ordinary car generates electricity to keep its headlights on. Some of the energy that would otherwise be wasted when the car is slowing down or braking is also captured as electricity and stored in the battery.

The ability to accelerate using both motor and engine combined lets Toyota fit a smaller, more frugal engine than the spacious Prius would otherwise require. This, plus the ability to regenerate energy whilst braking, are what make the hybrid design worthwhile.

It might sound inefficient and circuitous to charge batteries from a petrol engine just to then use that same second-hand energy to assist the engine, but in reality this can be a good compromise if the energy captured would otherwise be wasted as heat. It’s worth remembering that an ordinary engine is not a particularly efficient thing in the first place, when it has to speed up, slow down, or sit idling in traffic.

Specifications: Toyota Prius

Price: T3 - £17,782; T4 - £18,582; T Spirit - £20,682; all on the road including VAT

Seats: 5
Doors: 5
Bodystyle: Hatchback
Transmission: CVT automatic, front wheel drive
Insurance group: 7E (T3 and T4); 8E (T Spirit)
Service interval: 20,000 miles; oil change and safety check every 10,000 miles.

Top speed: 106mph
0-62mph: 10.9secs
Engine capacity: 1497cc
Peak engine power: 76bhp
Peak motor power: 67bhp
Maximum combined power: 112bhp
Width: 1725mm
Height: 1490mm
Length: 4450mm
Weight: 1300kg
Wheelbase: 2700mm

NCAP safety ratings:
Adult: 5 stars out of 5
Child: 4 stars out of 5
Pedestrian: 2 stars out of 4

VED band: B
Annual VED tax disc (08): £15
Company car tax rate (08/09): 10%
Official combined cycle: 65.7mpg
CO2 emissions: 104g/km
Fuel type: Hybrid - petrol/electric (tax code H)

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