It must be a challenging and confusing time to be shopping for a new car if you’re particularly keen to buy one that will save you a few quid at the petrol pumps and/or on company car tax.
Right now, most manufacturers have banished any vestige of the old NEDC-standard economy and CO2 emissions data from their brochures and websites, instead quoting NEDC Correlated numbers.
Oddly enough, these aren’t numbers generated by the old NEDC lab test at all; they're converted from new WLTP lab test results in order to represent something closer to the NEDC standard. It wouldn’t do, after all, if the car you were about to buy looked worse on fuel efficiency compared with the one you were giving up; and, to be fair, that probably wouldn’t represent its true performance on the road, either.
To make matters even more brain-addling, though, some manufacturers have already made the switch to properly identified WLTP statistics for fuel economy while sticking to NEDC Correlated CO2 numbers. That's because NEDC Correlated are the numbers relevant to both European manufacturer fleet emissions quotas and, for this year at least, company car tax liability.
So, in among all that, what strategy should Autocar take in order to try to deliver clarity amid the chaos? Well, we’ve been mulling it over. And we’ve decided the most sensible plan is to futureproof our reviews as much as possible by quoting only WLTP fuel economy and CO2 figures where possible; even if a manufacturer would prefer to give us NEDC Correlated data, we'll acquire data on the latest standard wherever we can.
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scotty5
It's certainly confusing.
Agree there's some confustion when looking at figures quoted in brochures right now because you must read the small print to know which figures are being referred to, but I cannot understand
"It wouldn’t do, after all, if the car you were about to buy looked worse on fuel efficiency compared with the one you were giving up"
But you should have already established that the figures quoted for the car you bought are no where near the figures you experienced. You'll have a good idea of the 'real-world' economy of your car, so that's the figure you should use for comparison purposes against the newer car. I can't see how it's going to look worse.
TS7
Well the conversion factor...
...from NEDC to Real World was around -25 to -30% (Official ~50 mpg, real world ~36 mpg). One assumes there will be a conversion factor from WLTP to Real World too, albeit a smaller percentage since the Real World figure will remain the same.
Peter Cavellini
About time really......
Have to say that finally a system where it should agree with what most of us knew years ago that mpg figures then when were at least 20% optimistic, the new system is almost spot on...
Peter Cavellini.
LP in Brighton
The only sensible option
Great. Adopting the WLTP figures is the only sensible thing to do to enable fair comparison between different cars using a standard controlled test. Frankly I'm not that interested in "real world" figures, or even road test ones, which are subject to different drivers and driving styles and different road, traffic and weather conditions.
I just wish manufacturers would be a little more consistent instead of quoting WLTP figures for fuel economy and NEDC-correlelated ones for CO2, effectively using two different measurement processes for the same thing. And let's hope there will be less cheating!
It's just a shame that WLTP (WORLD harmonised Light vehicle Test Protocol) has become a European standard rather than a global one, with other countries still using different procedures which cannot be compared.
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