hi there
how do you work it out? for a quick check, i just multiply 0.22 X Litres added, to give me the amount in gallons, then divide this figure by the mileage. not sure if this is correct or not. not sure where i got the 0.22 figure from either! Cheesy doesn’t really matter as my car only does 19 miles to the gallon! thank god for LPG!
re the trip computer. does it average the mpg over a set mileage? my scorpio averages the mpg over 500miles, so sometimes can appear different when worked out use the above method.
hth