Hyundai and Kia have published new zero-emission ranges for their Kona and e-Niro electric vehicles (EVs) after an error in the testing process was discovered - taking both vehicles below the landmark 300-mile barrier.

The Kia e-Niro and Hyundai Kona Electric had been given maximum ranges of 300 and 301 miles under the official Worldwide Harmonised Light vehicle Test Procedure (WLTP) combined all electric driving range test.

However, these have been recalculated after the Korean brands admitted that the independent organisation overseeing the process had “accidentally provided an incorrect testing methodology and then approved the results it generated”.

Both models had been tested for a disproportionate length of time on the WLTP ‘urban’ cycle – comprising lower overall vehicle speeds and a reduced energy requirement – as a result of the mix-up resulting in an overestimation of the vehicle’s all-electric range.

The inconsistency in the test cycles was identified due to ongoing homologation work.

Kia said in a statement that the official range of the e-Niro had now been reduced from 301 miles to 282 for the 64kWh battery model and from 193 miles to 179 for the 39.2kWh model.

The Kona Electric in 39kWh specification now has a combined range of 180 miles – down from 193 - while the 64kWh model is due to be recalculated with a range of 279 miles – down from 300.

No other Hyundai or Kia models are affected by the issue.