Trust in vehicle manufacturers in general, and their emissions and economy figures in particular, is at an all-time low. 

Hardly surprising when you can buy an SUV with a claimed ‘official’ economy of 156mpg and then struggle to get 45mpg in daily use; or a small car that is supposed to deliver 67mpg but produces about 40mpg in normal use.

In a way, you can sympathise with the manufacturers. With everything from VED to company car taxation based on ‘official’ CO2 figures, they are under enormous pressure to come up with engines that produce startlingly low CO2 emissions in the official test cycle. Design tweaks and software engineering can do just that in the highly prescribed, artificial and unrealistic test cycle, while leaving ‘real world’ emissions far higher.

But CO2 and MPG are directly linked, so if you come up with low CO2 figures, you have no choice but to publish correspondingly low MPG figures. And while no customers check their cars’ CO2 performance, quite a few keep an eye on MPG, and ask awkward questions about the gulf between claim and reality.

One ‘solution’ is to make trip computer mpg readouts outrageously optimistic. When my own car tells me it’s doing a very satisfactory 65mpg, the real figure is 56mpg. Some manufacturers are far more honest. Most owners believe what their car tells them, and that makes a mockery of ‘real mpg’ surveys of owners’ reported figures on websites. Another let-out is to qualify the ‘official’ figures in publicity material with small-print weasel words about how they “may not be representative of actual driving conditions.”

The proposal to replace lab tests with a real-world driving test might, one day, produce more realistic figures. But as it will have to be a standardised test, there will surely still be scope to tailor engine performance to the test routine.

It will take years for the official tests to improve. In the meantime, how can motorists discover the truth about MPG? In the past, magazine road tests used to be a good guide. I used to write these, with mpg based on brim-to-brim measurements over a minimum of 600 miles, including the 320 mile round-trip to the Millbrook test track, and the 40 mile test routine there.

We even corrected for odometer error (typically 4% over-reading). But fewer and fewer ‘proper’ road tests are published these days. I’m not aware of any magazine checking trip computer accuracy – something I’d certainly be doing if still in charge of road testing. The vast majority of car reviews seen by the public, in print and online, give no economy information apart from the ‘official’  figures

There’s a crying need for a high-profile economy event to reveal the real economy pecking-order. The old Mobil economy run and its variously sponsored successors used to do that. The nearest we come these days is the annual Fleet World MPG Marathon. It’s a brave attempt, but fails to attract a representative sample of cars or any significant publicity.

It needs to be beefed up into a high-profile event that gets such wide coverage that no manufacturer dares to ignore it. But for that it would have to be rigorously and independently organised, with enough funding for highly professional scrutineering.

It’s quite revealing that the motor industry pours billions into motorsport, yet can’t find a fraction of  1% of that to fund a real-world economy challenge that would have far more relevance to its customers. But maybe to gain trust, the funding needs to come from outside the industry. Looking within our own area, how about someone like James Dyson (surely soon to be Lord Dyson of Malmesbury…)? Or Stephen Fitzpatrick, founder of Bristol-based Ovo Energy, who has allegedly put £30m into the Manor F1 team.

So what would a Dyson or Ovo Efficiency Challenge look like? Crucially, it would provide a level playing field with absolutely no opportunity for fiddling. So all cars should be bought anonymously from dealers by the organisers, driven 1000 miles to reveal any problems and then given a standardised service and checkup by the organisers. Manufacturers would simply specify the model, pay an entry fee and nominate their drivers. To get the first event off the ground, the organisers could just go out and buy a representative selection of cars.

The format could be similar to the MPG Marathon, but over a longer distance of 1000 miles or more, visiting all four nations of the UK. Driving conditions should be truly representative, including motorways, city centres, A roads and B roads, up hill and down dale. The route should only be revealed at the start of each day. All monitored by in-car tracking technology, as on the MPG Marathon, with entrants free to choose their own route, but with sufficient compulsory waypoints to make navigational wizardry of only minor significance. 

The other thing that needs to be addressed is the results structure. There need to be classes for petrol, diesel, hybrid and electric vehicles. Because it’s the competition between technologies that is the really fascinating aspect of economy driving. There’s so much ignorance, misinformation and disinformation around: are modern high-tech petrol engines really as economical as diesels? Are hybrids the way to go? Joe Public certainly doesn’t know.

A budget in the low millions would be chicken-feed by F1 standards. Apart from providing results of unimpeachable integrity, it would allow truly effective promotion and PR to achieve the essential high media profile and public awareness and interest. And for the right sponsor – one like Dyson or Ovo – it would burnish an image of environmental concern combined with cutting-edge technology and efficiency.

Read also: MPG Marathon Musings

Western Group of Motoring Writers member John Kerswill achieved the highest overall mpg by a single-fuel vehicle in the 2016 MPG Marathon: 91.4 mpg (reduced to 88.9 mpg by time penalties) in a Mazda2 1.5D. He is a former editor of Diesel Car magazine and took part in the MPG Marathon with Ian McKeen co-driving.

John Kerswill
John Kerswill
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