Friday 23rd October 2015

NEDC mpg tests don't lie: Tell Me I'm Wrong

In the wake of a certain diesel-related scandal Dan argues the case for keeping the tests as they are

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It's always fun attempting to defend the indefensible so here goes nothing. I think lab-tested mpg and emissions figures are fine and all this hoo-hah and navel gazing about how we measure such things post-VW scandal is a waste of time. Is it too soon to weigh in with a Winston Churchill quote? Nah, let's get straight in there. As he once said, "democracy is the worst form of government, except for all those others which have been tried from time to time."

Hey, America, diesels are, like, great!

In respectful disagreement with my colleague Matt Prior on Autocar I think the same can be said for the current NEDC fuel consumption and CO2 figures. You know, the ones your car probably doesn't get anywhere near. The ones manufacturers work so hard to achieve and boast about in their marketing material. Similar ones to those Volkswagen engineered its cars to hit as and when required so it could sell diesel cars to Americans.

Usually this kind of thing has bubbled away in the background and in the consumer pages whose readers are exercised enough about their Kia Picanto not making the claimed mpg they feel moved to write and ask why. But, thanks to VW, emissions and mpg testing - and the claims made by manufacturers off the back of them - have become mainstream news. Meaning an awful lot of generally ill-informed but incredibly self-righteous stories about how the carmaking mega corporations lied to us.

They didn't really. They just engineered their cars to play the system and told consumers and testers what we wanted to hear. And their inspiration to paint their cars as greener than they actually are is not the fault of the test, more that of the politicians and legislating bodies who use the data as a basis for taxation and means of influencing people's buying decisions.

One example of playing lab figures to marketing advantage

Because hand on heart, anyone who really cares about what comes out of a car's exhaust pipe wouldn't drive a car. Who honestly selects a vehicle on its mpg or CO2 rating out of a desire to save the planet? Nobody. If fuel cost less than 20p a litre and VED was a flat rate we'd all merrily drive sod-off V8s and be environmentally damned. Like many do in countries where petrol is cheaper than water.

But in markets where a few mpg or g/km here or there can make the difference between a car being affordable or not it's straightforward logic manufacturers use a combination of engineering and marketing to convince us we can have our cake and eat it. Performance from a twin-turbo V8 that, by the numbers, seemingly is no more polluting than a 1.0-litre three-cylinder in a supermini? I'll have a piece of that!

And here's why the NEDC remains valid. Because, unrealistic about what a car will actually achieve or not, it's a controlled evaluation that applies a common standard to every car tested. Nobody drives a car like it is run on the test. But that's exactly the point. It's a laboratory test. How on earth could a 'real world' test ever hope to deliver consistent results?

Real world emissions differ - shock!

As it stands you can see how one car performs on the test against another of comparable price, performance and engine size. That may or may not indicate what you'll get out of it on the road. But it's at least a benchmark - a piece of evidence - to compare one car with another. As consumers we need to be more realistic and honest with ourselves. Scrutiny of facts, figures and the reasons we're being fed them is healthy, whether you're consuming news or stats used as marketing fodder.

The carmakers can't lay the blame entirely at the legislators' door though. They need to be more honest about how they use and publicise this data. If Mr Higgins in Tunbridge Wells bought his diesel supermini because the advert said it would do a certain mpg and it doesn't he's got a right to be cross. And we need to be more honest with ourselves and accept that, whatever engine our car has, if it's run of the mill hatchback, saloon or crossover it'll probably do somewhere between 30 and 40mpg in normal use and pump out an amount of noxious emissions in the process. So keep the test. Just ask more questions about how the results are used.

[Rolling coal image: GreenCarReports]

[MrTickle]

Agreement from me.

I have always found that the lowest official figure (urban) is usually what I average on every car I have owned, sometimes 1 or 2 more.

That is my benchmark and it seems to work, even on a VW group TDI!