Car Buyers' Guide: Big engines can be efficient

By Jack Biddle

As the Mazda proves, big can also mean more efficient


There was an article in the Herald with the headline "Kiwis ditching the gas guzzlers". The article provided fuel consumption comparisons between a number of large, commercial and small vehicles. What grabbed my attention were the comparisons between the three Mazdas featured - the Axela/3, Atenza/6 and the Demio/2. It listed the larger 2-litre Atenza as having a lower fuel consumption than the 1.5-litre Demio (6 litres/100km to 6.8 litres/100km). The Axela had the highest consumption of 8.4 litres/100km. Were those figures correct? If so, how can a bigger car be more fuel efficient than a smaller car?

- Tony

The answer
Yes, the figures were correct. What the article highlighted for me was motorists should not assume all small cars are super-efficient, neither should they assume all large cars are gas-guzzlers either.

The published figures included both New Zealand new and used import vehicles so to keep things simple for this article, I looked at the current claimed fuel consumption figures on the Mazda New Zealand website for their current new Mazda6, Mazda3 and Mazda2 range.

It showed the same trend, the Mazda6 having the better figures over the other two smaller models. Always remember, claimed fuel consumption figures should be used as a guide only as fuel usage can, and does, fluctuate due to several different factors.

The driver's right foot has one of the biggest influences on how much fuel can be saved or consumed. Learning to accelerate smoothly, avoid sudden braking, maintaining a constant speed and trying to avoid multiple short trips on a cold engine, are all things which will reduce fuel consumption regardless of vehicle or engine size. Add to that, keeping a vehicle well serviced and the tyres inflated correctly can also create fuel savings.

Mazda is a good example of a car company who has made some great fuel efficiency gains in recent times. Around five years ago the Mazda Motor Corporation made a public pledge to reduce the fuel consumption on its vehicle fleet by 30 per cent and have the complete range of new generation models in the showrooms by around 2015.

SkyActive engine.
SkyActive engine.

The result has seen the phased introduction of their SkyActiv that refers to a range of improvements made to a particular Mazda model including engines, transmissions and reducing weight but increasing strength with body design.

It's the sum of all parts rather than one single component that has seen fuel consumption figures tumble and the justification of the research and development time and financial investment. Implementing direct injection technology and increasing the compression ratio on petrol, while reducing it on diesel engines, has contributed to the improvement in not only fuel economy, but also engine performance and has allowed compliance with global emission regulations, particularly with diesels.

In New Zealand to date, we have seen the introduction of the SkyActiv technology in their award winning CX-5 range and the all-new Mazda6. Both have impressive claimed fuel consumption figures for both their petrol and diesel range. Next to follow will be the all-new Mazda3 and Mazda2 variants.

Mazda is certainly not the only motoring company to reduce fuel consumption and tailpipe emissions. While they have concentrated on improving the internal combustion engine, other manufacturers have spent the same, if not more, R&D dollars bringing hybrids and electric vehicles to the market in large numbers sooner.

Mazda6 wagon
Mazda6 wagon

Registered motor vehicle traders are required to display a fuel economy label at point of sale for cars manufactured after 2000 (except electric cars), provided the information is available. A star rating out of six is used for comparison purposes, with six stars for the most efficient cars down to a half-star rating for the worst performers.

As a guide, and based on a 14,000km annual travel distance and petrol at $2 a litre, a vehicle with a 2.5 star rating (12.7 litres/100km) will cost around $3560 a year in fuel costs. A more fuel efficient vehicle with a 4.5 star rating (6.8 litres/100km) will cost approximately $1890. For more information on fuel labels, go to the Energy Efficiency and Conservation Authority (EECA) website

Don't let fuel consumption be the sole reason to purchase a particular make or model of vehicle. At the end of the day a vehicle must meet a particular need and if that means a difference of say 1 litre/100km, then it may mean only an extra $1 paid. Working a little harder on driving technique can often create the biggest savings.

- NZ Herald

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