Fuel economy under the pump
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Manufacturers' fuel consumption vs real-life driving
The recent case of a Ford Kuga owner winning a Disputes Tribunal case against a Whanganui dealership highlights manufacturers’ fuel economy figures versus real-life driving.
The Kuga owner was told the fuel economy would be 7.7l/100km but the best he could achieve was 9.4l/100km, and he was awarded $6000 compensation.
So, can you really achieve the manufacturers’ figures?
Warning: If you ever attempt to achieve, or better, the claimed fuel consumption figures on a regular basis then be prepared to become very anti-social with your passengers.
Switching to full-on economy mode when driving for long periods is neither natural nor is it easy.
Plus, being both a safe and economical driver doesn’t always go hand-in-hand. In fact, I have seen the exact opposite with some fuel-conscious drivers doing some crazy things in an effort to save fuel, while the safest driver can be heavy footed.
I was involved in organising past Energy Wise Rally’s and many independent fuel consumption tests for the industry, so I know first-hand the driver concentration required to better or even equal manufacturers’ claimed figures on a regular basis.
I remember one competitive driver in a past Energy Wise Rally (EWR) who told his wife she was welcome to be his compulsory passenger/navigator, so long as the radio remained off and she didn’t talk to him during stages unless it was absolutely necessary.
Yes, silence is certainly golden inside the cabin to help maintain those required high levels of concentration.
For the average motorist trying to achieve the best fuel consumption possible, results hinge on a number of different factors such as:
■Weather (can work for or against)
■Driving conditions (congested or open road)
■Terrain (flat versus twisty and hilly)
■Tyre pressures (correctly inflated)
■Tyre construction (fuel saver versus non fuel saver)
■Engine oil quality (grade of oil)
■Extra weight (less is best)
■Driver seating position (relaxed)
■Type of footwear used (light and comfortable)
And the most important of all:
■Driver ability (smooth throttle control, anticipation, momentum, consistency)
■Who is paying the fuel bill (company vehicle or privately owned)
Manufacturers claimed fuel consumption figures are generated by laboratory testing under specific controlled conditions and temperatures. It includes short spells of cold start, acceleration, deceleration, steady speed and idle running.
The urban (around town), extra urban (higher speeds) and combined fuel consumption figures are calculated from the results gained. Testing in terms of total distance travelled is completed in less than 20km of equivalent on-road driving.
So in real world driving, there are many different on-road variables that can influence fuel consumption that are not taken into account when those claimed figures are published by the respective manufacturers.
For consumers, this means claimed figures should only be used as a guide when comparing vehicles of similar style, power and size.
To put our skills to the test, Driven decided to do its own in-house testing to see just how close we could get to achieving manufacturers’ claimed figures.
2012 Nissan Qashqai fuel consumption was 7.2l/100km.
The rules were simple: air-conditioning on, one extra occupant in the vehicle and 15kg of extra weight added.
Where possible, maximum speed limits were adhered to at all times.
Plus, we decided to use a privately owned vehicle rather than involve a new vehicle distributor.
Details of the vehicle used:
• 2012 Nissan Qashqai
• Constant variable automatic transmission (CVT)
• Odometer reading: 32,000 kilometres
• Claimed combined fuel consumption: 7.6l/100km (figure from rightcar.govt.nz)
Our midweek drive started in West Auckland around 9.30am and headed out through busy urban roads before joining the motorway at Pt Chevalier (via the Waterview tunnel construction site) and heading south toward the Coromandel. We stopped for a coffee break at Takanini before heading to Kopu, over the Kopu-Hikuai hills and onto Whitianga.
The car was parked for a night then taken down to the local shops the following morning followed by a sedate cruise around town, and used to attend a dinner date that night.
All up, just over 200km were travelled.
Average fuel consumption achieved was 7.2l/100km, which is lower than the claimed figure and a big tick for the Qashqai.
It’s such an easy car to drive and to maintain that all important momentum. This test result didn’t surprise me.
It demonstrates how the average driver can go close to achieving claimed figures if they put their mind to it, drive appropriately and conditions are in their favour.
The other important point to remember is good fuel consumption figures are impossible to achieve when consistently using a vehicle on short, stop-start trips around congested roads.
This is where the petrol/electric technology (hybrid) has clear advantages and to a lesser extent those vehicles fitted with automatic stop/go systems.
So can you trust the claimed fuel efficiency figures?
Yes, if they are used as a guide only.
There are definitely some manufacturers who can achieve better claimed figures than others, which can turn into savings at the pump.
But it’s unwise to assume those claimed figures are automatically achievable regardless of how well a vehicle is driven, or the way it’s treated.