The trip computers are good but they aren't aren't 100% accurate.
I brimmed my last tank with v-power which took 51.40 litres then when the petrol light came on i brimmed with tesco 99 which took 51.90 litres.
So i clocked 315.4 miles and used 51.90 litres
51.90/5.54=9.37 gallons
315.4/9.37= 33.7mpg

My trip computer was reset at the time of fill up and after the 315.4 it read 31.9 (on mode 2) so you could all be getting even more than you realise

Any hows i'm doing the same test again with the tesco 99 fuel to see which is best for my pocket and yes i am tighter than a submarine door
