At 90kph you should be a good 20% better than WLTP.
I struggle to see how some people can get such bad efficiencies.
I'm sure I could probably save people thousands by teaching them how to drive efficiently so they can buy smaller batteries, but people really don't want to believe their car's efficiency is a function of their driver skill.
... my average is slowly creeping up on my commutes now at 6.7mi/kWh, and my average speed on those commutes is also creeping up from about 25mph as I am learning how to eek out the corners of the Zoe's efficiency envelope.