Are the official MPG figures fact or fantasy?

Did you ever wonder, just how is fuel consumption calculated? And why doesn’t my car ever reach those figures? Our friend Tim Shallcross, from the Car Clinic, explains why*

Since the late seventies, manufacturers have had to tell us the fuel consumption for their products. This requirement was initially prompted by the oil crisis of 1973, then by concerns over the environment. However, fuel consumption varies considerably according to speed and so on, so in order to give a like for like comparison, various standard tests have been introduced over the years. One of the first was the fuel consumption at a constant 56 mph – a strange and rather uninformative figure, since we tend to drive well below that speed in towns and somewhat above it on motorways. The latest standard test was introduced in 2001 and is the same right across the EU. It claims to be more representative of real driving conditions than previous tests; that may be true, but being better than something that’s wildly inaccurate still doesn’t necessarily make it accurate. But how, exactly, does it work?

The testing isn’t done by denim clad curly haired journalists pushing the car to the limit out on the open road; it’s done by very serious folks wearing white coats in a laboratory. They drive the car on a rolling road – the car’s wheels sit on rollers that simulate the resistance of an actual road. There are two parts to the test. The first starts with a cold engine and is supposed to replicate a drive through a town with a specific series of starts and stops and steady speeds for two a half miles. The maximum speed is 31 mph. The second part is intended to replicate out of town driving with speeds up to 75 mph (presumably to allow for the fact that it’s EU wide.) The results for the two parts are quoted, together with a combined figure which is the average of the two. This test is also used to calculate the CO2 figure which is used as the basis for Vehicle Excise Duty (Road Tax) and company car tax. The three mpg figures and the CO2 figure must all be shown clearly in any printed advertisements – and the adverts often promote the CO2 figure in particular, to appeal to company car drivers and to private customers wanting to “go green” and get into a lower road tax band to save some money.

Even the Vehicle Certification Agency (VCA) admits that the fuel consumption achieved on the road will not necessarily be the same as the official test results

However, even the agency responsible for the figures, the Vehicle Certification Agency (VCA) admits that “…the fuel consumption achieved on the road will not necessarily be the same as the official test results”. If the fuel consumption won’t be achieved on the road, nor will the low CO2 emissions. So, why don’t we all manage to achieve the fuel consumption shown on the ads? There are many reasons.

First of all, a rolling road doesn’t really simulate real world conditions. Wind resistance can be simulated to an extent, by extra resistance from the rollers, but this doesn’t include the effect of an open window or a roof box, and they can make a big difference. A roof box can increase fuel consumption by as much as 20 % at 70 mph. As drivers, we often have extra weight in the car. That could be a passenger or the shopping or a set of golf clubs. Weight makes quite a difference when you’re starting and stopping, but for the official mpg test, the car stays still and the load is simulated by the rollers, which means that the impact of any extra weight isn’t picked up during the testing. That can make a difference when there are several variants of a model. Not every car has a sample tested – just one car that is representative of the range – usually just a manual and automatic example for each engine type.

The major factor is that the manufacturer generally wants the test to give the best possible figures

Extras fitted to higher spec. versions that increase weight, drag or engine load are not taken into account. Equipment such as air conditioning, heated rear windows and even headlights use significant amounts of fuel, but are generally (although in fairness, not always) ignored. But the major factor is that the manufacturer generally wants the test to give the best possible figures, and it’s possible to set the car up to perform at its most frugal for the conditions of the test and squeeze into a lower VED bracket, even if those ratios don’t give the best fuel efficiency for real driving. For example, selecting the ideal gear ratios for the conditions of the test cycles may give an excellent set of figures for the advert, but can result in a car that’s awkward to drive at normal speeds – how often do you read reviews of cars that are “boomy” at motorway speeds? Or a car might be set up to do really well on the “out of town” section to give an impressive overall figure, but if it’s driven for much of its life in inner city traffic jams, you won’t be getting the advantages designed into it.

Finally, the test is conducted by a technician who is concentrating on getting the best figures, and knows how to do it. Accelerating reasonably, changing gear as early as possible and minimising the use of the brakes are all techniques we could out into practice out on the road, but few of us do.

Now, all this might seem academic and the figures certainly do have a useful function in that they give good method of comparison between models, since all are doing the same test. They also give you a good target to aim for if you want to drive economically and in an eco-friendly fashion. But they can also be quite misleading.

Take hybrid cars – they use a combination of a petrol engine and electric motor and are generally thought to be very “green”. They’re catching on in the UK now, particularly the Toyota Prius, and they’ve achieved great popularity in the US for a few years now. However, many hybrid owners on both sides of the Atlantic are starting to ask why they’re not getting the miles per gallon suggested by the adverts.

The hybrid concept is very good when you’re crawling along in traffic under 25mph

The reason becomes obvious once you look properly at the figures. For the Prius, the overall fuel consumption, as given by the standard laboratory tests, is a very impressive 65.7 mpg. But owners report that they get nowhere near this – especially those who do quite a high mileage. Why? Well, the overall figure is the average of the “urban” figure of 56.5 mpg and the “extra urban” figure of 67.3 mpg. Both seem impressive until you start to look at other cars – especially small to medium diesel powered cars. Then you see that the urban figure of 56.5 mpg is outstanding and virtually unbeaten by any other car, but the out of town figure is not that impressive by today’s standards. Many manufacturers have similar sized cars that achieve 68, 69 or even 70 mpg or more on the extra urban cycle. That’s because the hybrid concept is very good when you’re crawling along in traffic – when you’re stationary it’s not using any fuel at all and at the pace of a typical urban rush hour crawl it’s running for most of the time on very efficient zero emission electric power. But above about 25 mph at most, the car is running entirely on the petrol engine, at lower efficiency then a good modern diesel. In fact, if the out of town cycle included a long steady speed section, simulating perhaps 20 or 30 miles of motorway, many quite ordinary cars would out perform the hybrids. In town, they’re great; out of town you’re carrying a lot of heavy batteries around for no great benefit. Owners who drive from the suburbs to the suburbs will do very well in a hybrid. Owners who drive from their out of town executive home to the out of town shopping centre or small town high street office would be better off with a modern medium size diesel car – or even one of the very latest “advanced gasoline” engines.

So, don’t believe everything the mpg figures on the adverts tell you – look a little closer and work out the best type of technology for the type of driving you do. And always remember that if you’re not getting the claimed mpg, you’ll also be releasing more climate changing CO2 , so getting the right technology is important if you want your driving to be genuinely eco-friendly.

*reprinted by kind permission of the author, Tim Shallcross, for We Are Futureproof. The article first appeared in the Times Online Driving section. Tim is Head of Technical Advice at IAM

LCVP Webinar reveals which car-makers are making CO2 info easy to find on their websites

Important new research has been revealed this week by We Are Futureproof and our partners in promoting cleaner cars.

At a special ‘webinar’ on Wednesday 27 January, Dr Ben Lane presented the results of his study of car-makers’ websites, showing how well each manufacturer is doing in providing CO2 information to its customers

We Are Futureproof, the Energy Saving Trust and Friends of the Earth Europe have come together to fund Ben’s research, via his consultancy and research company Ecolane.

Sorely needed, we all agreed, because car-makers and advertisers consistently object to rules putting CO2 information on adverts by arguing that consumers would rather use the internet to find out the fuel efficiency of cars.

We’re not convinced by this. Figures on efficiency and emissions can be provided in a few words of text or a simple graphic, both of which are easily included in artwork for ads (and our previous research showed a graphic was much better at conveying the info).

We argue that this data should be included everywhere a car is promoted, including adverts AND websites

New regulations since 2008 mean that CO2 info has to be included on billboard and magazine adverts, and we’ll be reporting on how well advertisers have complied with these soon.

But the regulations don’t yet cover websites. So, the question remains: if the web is the preferred way for car-makers to give us efficiency data,  just how well are they doing?

Ben’s study has looked in depth at how easy the public finds using the websites of all major car manufacturers in the UK.

Seventy-nine volunteers attended research sessions in person and 363 people carried out some very clever online tests, which tracked their mouse clicks and timed them as they tried to find CO2 figures for specific models.

Altogether more than 1,000 interactions with car-makers websites were carried out, making this a robust survey of the current state of things.

The average time taken to find the data ranged from 74 seconds for Lexus to 469 seconds for Alfa Romeo - nearly 8 minutes!

Manufacturers of lower carbon vehicles were found to be no more successful in accurately informing users of their websites of CO2 information than manufacturers of high emission vehicles.  Smart, Nissan and Alfa Romeo were found to be the ‘bottom three’ in terms of accessible carbon emissions data.  These sites tended to have lengthy look-up times in finding CO2 values and over-use of Flash technology and PDF downloads to convey information.

Mini, Kia, Lexus and Honda websites were those that participants found easiest to access CO2 information. The average time taken to find the data ranged from 74 seconds for Lexus to 469 seconds for Alfa Romeo - nearly 8 minutes.

According to Marian Spain, Director of Strategy at the Energy Saving Trust: “Nowadays most people do initial online research when looking into buying a new car. This research shows that in many cases, finding out the running costs of cars and their impact on the environment from the car manufacturer website is like looking for a needle in a haystack.”

“Cars account for one sixth of all the UK’s carbon emissions. The gulf between the most efficient family car and least efficient family car is two tonnes of carbon dioxide emissions and £1,000 a year – that’s worth knowing about. At the same time, even manufacturers of low-carbon cars aren’t making the efficiency of their vehicles at all clear. I want to see the straightforward fuel economy label next to every car model viewed online so people can make informed choices.”

Our call for change is also supported by Consumer Focus. Their spokesperson Lucy Yates told us: “Clearly the car manufacturers have a long way to go if they are to help consumers make greener choices. Only half of consumers were able to find accurate information about a car’s CO2 emissions on the manufacturer’s website.

“The industry must provide clear, credible information as standard so it’s easy for consumers to compare a car’s green credentials.”

While the webinar has now passed, the full research report has been published and is available for download here.

Sian, for We Are Futureproof

The new Tesla Sedan is on its way

What with the economic meltdown in the US, and the dire crisis in innovation that most of the car industry finds itself in, we were glad to hear this week that Tesla Motors finally secured a $450million loan from the government that will allow them to set up a manufacturing plant in Southern California. This will help usher in a new era of electric vehicles that go far beyond the hybrids, let alone the snobby Porsche roadsters out there.

Imagine putting your family of 7 into a new Tesla Sedan for a family trip. 300 mile trip? No problem. Need to charge the car up for another 300 miles? 45 minutes later you’re out on the road again. And acceleration? Is 0 - 60 mph in under 6 seconds ok?

The price tag may put a few people off - $50,000 - though is far cheaper than the original Roadster.

In case you’re interested, volume production of the Model S is planned to begin in 2012 with a target production capacity of 20,000 vehicles per year by the end of 2013. Plenty of time to start saving up.

Blake, for We Are Futureproof

Are Lithium batteries an environmental problem for EVs?

Here at We Are Futureproof, my colleague Sian and I have been sticking our necks out and supporting electric vehicle technology. However, that’s not a position readily shared by many environmental groups or even the Green political party. Several NGO’s are skeptical of progress in general, and remain glued to wholesale demand reduction for cars until we all resort to walking, cycling and taking the bus, as if we will someday see the backside of the automobile. But if we assume that cars will be around a while longer, albeit transformed in design and power train, then we’re all for the transition away from running on liquid fuels to powering up on electrons. And indeed, the transition to the electric vehicle (EV) looks inevitable.

Besides the ever present range issue, where most first generation EVs resemble milk floats or golf carts with a range under 100 miles, there is another slight sticking point that comes up in conversations nowadays and that is around the supply of materials that go into the batteries for electric vehicles. Currently, EV’s use lithium ion batteries, and lithium has been quite expensive.

Much as today’s drivers are hostage to scarce, increasingly costly oil, will tomorrow’s drivers be reliant on scarce, increasingly costly lithium?

According to ecomii.com, around half of an EV’s manufacturing cost comes from its lithium ion battery. Mass adoption of EVs depends largely on improving the competitiveness of their batteries. But lithium is also used in batteries for other electrical technologies including laptop computers, digital cameras and cell phones. As demand rises faster than supply, price increases. Unfortunately the supply of lithium is limited by both geological and political factors.

While Lithium is a naturally occurring element, it is a finite natural resource: only so much of it exists in the world. And here’s the crunch point for many environmentalists  - half of the world’s known Lithium supply is located in Bolivia, in a nature reserve.

Source: Meridian International Research, 2005 levels

Will we endanger the environment as an unintended consequence of our desire to move away from oil?

Some 70% of lithium deposits can be traced to what is known as “The Lithium Triangle”, a tiny area on the borders of Chile, Bolivia and Argentina. The other significant supply of Lithium is found in Tibet. China is just now starting to exploit a series of some 33 brine lakes in and near Tibet, again in high, dry and very remote deserts. Their 35,000 ton lithium processing facility could, in time, make them the largest lithium producer on the planet. These are two remote and fragile environments, and any major mining operation would result in irreversible and widespread damage. Extraction of lithium within “the Lithium Triangle” is said to require some two-thirds of the area’s drinking water and Sulphur Dioxide is a major by-product of production. What this means, according to www.sustainableluxury.net, is that like oil, lithium production has a cap and with the growing demand for electronic goods it is estimated that realistic lithium carbonate production will only be able to produce a small fraction of the demand suitable for use in EVs. Demand for batteries is the fastest growing resource request for lithium and we still have not seen a widespread roll out of EVs.

“There is an insufficient supply to accommodate the wholesale conversion of the entire world’s auto industry from internal combustion engines to battery-powered electrics” William Tahil

If there is a marked increase in demand for EV technology, we will hit Peak Lithium like we have hit peak oil. This concern hit the airwaves when a report was released from Meridian International Research, a renewable-energy think tank in France. In 2008 William Tahil produced a report for Meridian, concluding that the world does face a shortage when vehicle demand is added to considerable consumer electronics demand. Estimates of global reserves vary, and Meridian is putting the number at 4 million tons rather than the 20 million cited by many of the more sanguine reports. Tahil says that while increased production can keep pace with EV production of a few million units per year, there is an insufficient supply to accommodate the wholesale conversion of the entire world’s auto industry from internal combustion engines to battery-powered electrics. “There’s enough for a niche market,” Tahil says, “but nothing close to enough for the mass market.”

Nevertheless, many financial analysts who have done studies on the outlook for future Lithium production say that worries about scarcity are overblown. In a blog by allcarselectric.com, Neil Maguire, vice president of business development at Imara Corp., a lithium ion battery startup in Menlo Park, Calif., says supply is sufficient to meet near-term demand. Beyond that, if the volume of electric vehicles soars so much that lithium supplies become an issue, older lithium ion batteries can be recycled for the raw materials in them.

If Not Lithium, What Then?

What about research looking beyond lithium to other materials? in 2005 Meridian researched the various battery technologies for electric vehicles and of all the chemistries it analyzed, sodium nickel chloride and zinc air stood out. The first option, sodium nickel chloride was developed in the 1980s and is known as the ZEBRA battery. In an interview with evworld.com, Tahil characterizes the ZEBRA battery as relatively cheap and proven technology with a potential cost in mass production of $150/kWh compared to $350/kWh for lithium ion. The ZEBRA-class battery also doesn’t require the same level of thermal-runaway protection that lithium does. “The sodium nickel chloride is fail-safe in overcharge and over-discharge. It tolerates cell failures, so that performance degrades, but there is no safety issue, which there still is with lithium ion. Tahil agreed that while nickel is the most expensive part of the battery, it is a metal that is far less constrained than lithium. “It’s a major industrial metal that is mined all over the world. You’re talking an order of magnitude (1000x) more availability of nickel than lithium.”

Another technology to consider is Zinc-Air

Zinc-Air batteries are currently used in hearing aids. According to Tahil, “the great attraction of zinc-air is very high energy density - four-times the energy density of the best lithium ion batteries available. Zinc also happens to be “extremely cheap and extremely abundant.” The chief drawback of zinc-air is its short cycle life, comparable to a conventional lead-acid battery at upwards of 500 cycles. “This is an area where work needs to be done. “But it’s a question of economics and costs, as well,” he continued. Because zinc is so cheap and abundant, it might actually make economic sense to have the battery replaced once a year when the car goes in for service. The zinc oxide can be recycled and reprocessed into new batteries. “There is already a well-established zinc recycling industry.”

What does the future mobility system look like given the resource constraints that we face?

In reading the various reports and blogs, it seems there are a variety of views about Lithium and the potential hazards of mining the resources as well as a potential scarcity of supply. While Lithium is presently the front runner, there is ongoing research in new materials and technologies which could be cheaper and more widely available. None of this research suggests, however, that we should shy away from EVs. Gary Kendall, author of Plugged In: The End of the Oil Age, suggests that the overall point is that electrification is not an option; we have to do it because we need highly efficient, zero-emissions mobility solutions that are compatible with the full range of physical renewable energy technologies. We also have to live within any constraints imposed by nature - that’s true whether we are talking about lithium or carbon.

So, according to Kendall, the right approach to the question is: what does the future mobility system look like given the resource constraints that we face? This is a much more interesting discussion.

Blake, for We Are Futureproof

Mercedes guilty of exaggerating emissions of new cars

For two years, WRFP has been working on cleaning up car adverts. We’ve been working closely with our lawyers to ensure all adverts have CO2 information, according to the requirements of the EU Directive. We have also been attending a lot of stakeholder meetings asking the question: “How can we update Green Guidance in the UK to make sure the guidelines are protecting consumers from misleading and unfounded  environmental claims.”

In a recent case, the Advertising Standards Authority (ASA) reported that German car manufacturer Mercedes-Benz has misled the UK public by claiming low emissions for a range of executive cars that are among the most polluting on the road.

“Its a pleasure, but not a guilty one,” the automaker said in a magazine advert for the E-Class Saloon range priced between £26,000 and £47,000, adding that its emissions were “down to” 139grams of Co2 per kilometre.”

Following a recent complaint the ASA investigated and found that only two out of a possible 24 E-Class cars corresponded with the emissions figures, warranting an E band in the Government’s banding system which ranges from A to M. Some were in the M band, the highest set by the Department for Transport (DfT) to warn drivers about high levels of fuel consumption, taxation and pollution.

Car-makers have frequently had ads for their vehicles banned for making dubious environmental claims, particularly for four-wheel drive and executive models criticised by campaigners for high fuel consumption. In the latest case, Mercedes-Benz suggested that drivers would switch to its new range safe in the knowledge that they would be helping the planet. “CO2 emissions for the range are down to 139g/km*, which means its better for the environment. It also means you pay less tax,” the company said.

The model shown in the advert was a Mercedes-Benz E250 CDI Sport, which has emissions of 139g a kilometre. A footnote stated that the range’s emissions varied from 139g to 261g a kilometre. Mercedes-Benz told the ASA it believed it had taken reasonable steps to substantiate its claims and had not misrepresented emissions levels. However, the ASA said that the claim that the E-Class was “better for the environment” was likely to be understood as meaning the range as a whole was low in emissions compared with previous models and rival models. Depending on model, fuel, gearbox and tyre sizes, only two vehicles out of the 24 in the range compared favourably with competitors’ vehicles of a similar class, while “a number of vehicles in the range had emissions levels that were at the higher end of the DfT emissions bandings.”

The ASA acknowledged the footnote. “However, we considered that the headline claim would give the impression to readers that a significant proportion of the range had achieved the lowest emissions figure, or a figure that was relatively low for the class, when that was not the case.”

The ad was banned under rules on truthfulness, motoring and environmental claims.

Blake, for We Are Futureproof