Get thrifty on the road

The fuel-efficient VW Jetta sedan comes with a choice of either a 2-litre petrol or diesel engine.

As the price of fuel goes through the roof the most frequent question I am asked is: what's the most economic petrol or diesel car on the road in New Zealand?

The only data available for New Zealand conditions in recent years is that from the Energywise rallies of 2002 and 2004 (see link below) when most of the major carmakers entered models in the 1600km North Island event.

The rally is held every two years and run by the Motor Industry Association, supported by the Energy Efficiency and Conservation Authority (EECA), Gull Petroleum and the Automobile Association.

Its purpose is to highlight the low fuel consumption of new cars, providing real-world results that indicate what could be achieved by vehicle owners. It is not an economy run, where cars and drivers sit at 50km/h for mind-numbing hours on end.

The four-day route in 2004 took the cars and their two occupants from Auckland to Wellington and back, using an indirect route which took in city driving, country roads, and everything else in between.

Petrols, diesels, petrol-electric hybrids and bio-fuel cars competed against each other in their respective classes, so that direct comparisons could be made.

Fuel consumption figures were adjusted for carbon dioxide (CO2) emissions. This allows the full environmental impact of the vehicle to be taken into account.

Different fuels produce different amounts of CO2, one of the greenhouse gases that contributes to climate change.

The overall Environment Award goes to the car which achieves the lowest fuel consumption (adjusted for CO2 ), irrespective of class.

There was a largely ho-hum response from consumers to the first two rallies - a litre of 91 unleaded in 2002 cost a few cents over a dollar and diesel cost around 80c. The price remained reasonably stable in 2004.

But the third rally this November is likely to take on new economic significance for car buyers. . Talk of $2 a litre by Christmas would double the price of petrol in seven years.

Forty years ago, a 10c hike in a gallon (4.5 litres) would have moved the hands of the doomsday clock forward and caused resignations and snap elections.

The most fuel-efficient and greenest car in the country is the petrol/electric Toyota Prius, based on results of the 2004 Energywise rally.

The 1.5 litre Prius sedan was piloted by former Formula One ace Chris Amon, who recorded 4.02 litres/100km (70.3mpg) in 1600km of driving.

Deadheating for second was another Prius and a 1 litre Daihatsu Charade hatchback, both recording 4.39 litres/100km (64.4mpg). Both Prius models and the petrol-powered Charade finished first and second for environmental friendliness.

A turbo-diesel car that didn't enter into final calculations because it is not yet on sale in New Zealand actually finished second. The 1.5 litre Hyundai Getz used 4.18 litres/100km (67.5mpg). A 1.3 litre Getz using biofuel used 5.86 litres/100km (48.2mpg).

Another turbo-diesel, the 1.9 litre Peugeot 307 hatchback, came in third for fuel useage, recording 4.61 litres/100km (61.3mpg). The Skoda Fabia RS, which uses a 1.9 litre Volkswagen diesel engine, used 4.79 litres/100km (59mpg). The VW Golf with the same engine swallowed 5.22 litres/100km (54.2mpg).

The small Honda Jazz was one of the thriftiest petrol cars, the manual model using 4.85 litres/100km (58.2mpg) and the automatic 5.09 litres/100km (55.5mpg). Its consumption was similar to that of the petrol/electric Honda Civic Hybrid, which used 4.99 litres/100km (56.6mpg).

The 1.8 litre Toyota Corolla used 6.28 litres/100km (45mpg) and the 1.5 litre Honda Civic 5.86 litres/100km (48.2mpg). A 2 litre Mitsubishi Lancer used 5.83 litres/100km (48.4mpg).

The Lotus Elise sports car, a desirable lightweight with a top speed of 220km/h and a zero-to-100km/h sprint time of around five seconds, sipped 5.69 litres/100km (49.7mpg).

Of the medium-sized cars, the 2.4 litre automatic Honda Accord Euro clocked 6.7 litres/100km (42.1mpg), the 2.3 litre Mazda6 Sporthatch 6.57 litres/100km (43mpg), and the 2.2 litre Peugeot 407 7.03 litres/100km (40.2mpg).

The V6 Mercedes-Benz S320 headed the large/luxury class, its 6.46 litres/100km (43.7mpg) ahead of the V6 Honda Accord with 7.66 litres/100km (36.9mpg), the Holden VZ Commodore with 8.24 litres/100km (34.3mpg), and the Ford Falcon XR6 Turbo with 9.75 litres/100km (29mpg).

In 2002, racing driver Greg Murphy nursed the throttle of a 5.7 litre V8 Commodore through much of the first rally to record fuel usage of 9.88 litres/100km (28.5mpg).

The most recent new arrival to the country's car park is the VW Jetta sedan, launched last week. It comes with the choice of 2 litre petrol and diesel engines. VW is claiming fuel useage of between 5 and 6 litres /100km (50mpg) for the turbo-diesel.

Some tips to save fuel:

* Avoid short trips: Cars use much more fuel when the engine is cold, and mechanical wear is at its most excessive before the engine reaches normal operating temperature.

* Drive smoothly: Make sure you accelerate smoothly. Jumping on the throttle from rest can cause useage to soar to up to 90 litres/100km (3mpg). Change gear early (but don't labour the engine). If you drive an automatic, allow the transmission to change up early by accelerating on a light throttle.

* Look ahead: Check what's happening, maintain a safe following distance and you'll keep at a more constant speed. This uses less fuel than accelerating and braking all the time. Allow the car to slow gently over a greater distance with minimal use of the brakes by anticipating red lights, speed limit changes and traffic stoppages.

* Corner smoothly: Don't brake hard for corners and accelerate out. Slow gently, negotiate and exit the corner on a light throttle.

* Make hills work for you: Lift off the throttle as you crest the hill and use the car's momentum to get you over the top. Build up speed before an uphill stretch.

* Love your car: A little love goes a long way. Keeping your tyres at the right pressure saves fuel, as does having your wheel alignment and engine tuning checked regularly.

* Watch your air conditioning: Only use air conditioning when absolutely necessary, as it can use up to 10 per cent more fuel. Other features such as the rear window demister can also be a drain, so make sure you switch them off when they've done their job.

* Keep your load down: Sounds obvious, but a heavier vehicle means the engine has to work harder. So take those golf clubs out of the boot after the game, and remove the bike rack when you're not using it.

* Reduce idling time: If you're going to be stationary for more than 30 seconds, switch your engine off.

* Don't speed: Driving faster doesn't necessarily mean you'll get there quicker. By travelling at 100km/h instead of 110km/h you can cut around 13 per cent off your fuel bill.