I wonder if Motability have decided to do this because of people returning cars that don’t get the claimed manufacturers MPG, on the grounds that the car is not as advertised & hence unsuitable.
For my EV the manufacturer has the usual inaccurate WLTP rates, but they have also published a calculator that shows what the real consumption will be at various temperatures & driving styles and I’m thankful that they have as it’s very accurate (unlike the GOM).