No, I’m comparing real world, measured by inputting mileage and litres purchased into fuelly alongside OBC readings. I had two Discoveries, both covered around 7-8k miles. The one that did perhaps 5k of its 7k on motorways averaged 32.9mpg lifetime. Most motorway runs were high 30s. The one that did perhaps 1k out of 8k on motorways and the rest urban managed a lifetime average of 23.4mpg.
Given what the other poster said, it seems that BMW designed an astonishingly inefficient car in the X1. I had a 320d that spent 75% of its life with me on motorways and over 68k tracked miles it averaged 53.7mpg.