Kia Motors Europe and Hyundai have announced reduced ranges for their electric SUVs after an error in the homologation process was discovered.

Both the Kia e-Niro and Hyundai Kona Electric had been given ranges under the official Worldwide harmonised Light vehicle Test Procedure combined all electric driving range test.

However, these have been recalculated, meaning the official range of the e-Niro falls 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.

The manufacturers say the independent organisation overseeing the process accidentally provided an incorrect testing methodology and then approved the results it generated.

This led to both models being tested for a disproportionate length of time on the WLTP ‘urban’ cycle – comprising lower overall vehicle speeds and a reduced energy requirement – resulting in an overestimation of the vehicle’s all-electric range.

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

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