New method of MPG calculations WLTP

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Thu 25 Jul 2019 13:19
New method of MPG calculations WLTP - Simon Bratt

Maybe most people know this, but its taken us days to work this out.

Since Sept 2018 new cars have to use the new method of calculating MPG called WLTP.

Cutting a long story short, the quoted manufacturers MPG on here look like they are using the old NEDC figures. the New ones are much more realistic.

Ive checked Vauxhall and Seat and both are using the newer WLTP figures. So that's why if i look up a Grandland X for example, honest johns manufacturing figures don't tie up with the manufacturers figures.

Will Honest John be updated and when? ( i know I may have to email them)

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Thu 25 Jul 2019 14:16
New method of MPG calculations WLTP - Leif

And on a related note, the old figures for hybrids are absurd as they are based on using battery power for a substantial portion of the journey, and hence come out with fantasy values. Apparently some manufacturers have withdrawn hybrids from sale in the UK as they no longer attract tax relief, and not too soon.

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Thu 25 Jul 2019 14:38
New method of MPG calculations WLTP - Manatee

Will Honest John be updated and when? ( i know I may have to email them)

There's probably no simple solution unless the database is expanded. WLTP figures don't exist for cars that were taken off the market before the relevant date.

What really matters is the real mpg, which shouldn't generally be affected.

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Thu 25 Jul 2019 14:55
New method of MPG calculations WLTP - daveyjp

As you acknowledge WLTP had a start date. For vehicles manufactured on dates which straddle this date you will get different figures.

Both tests are nonsense and if you want a real world estimate use the HJ real MPG data.

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Thu 25 Jul 2019 20:40
New method of MPG calculations WLTP - Leif

As you acknowledge WLTP had a start date. For vehicles manufactured on dates which straddle this date you will get different figures.

Both tests are nonsense and if you want a real world estimate use the HJ real MPG data.

Actual mpg depends more on driving style, I guess most people drive rather inefficiently.

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