Why are their differing mpg ans CO2 figures for some models?

I'm looking to buy a used Hyundai i10 but am confused by the differing mpg and emissions data for the 2017 - 2019 1.0-litre models. I did not think that the i10 had been changed during this period. Is it just that the ways of measuring have been altered over these years, or are the 2017 models really more efficient than the more recent models? Thanks.

Asked on 13 September 2020 by Helen Osburn

Answered by Dan Powell
The differing mpg and CO2 is down to the way the cars are officially tested. Older vehicles are assessed under the old NEDC test, while newer cars are tested against the more realistic WLTP standard: www.honestjohn.co.uk/what-is-wltp-new-fuel-economy.../

This means lots of cars have two separate CO2 and mpg figures.
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