Just bought car and am totally confused as  I filled up £85 deisel and gauge shows only 456 miles to 0 

Is this right 

Grateful for any clues 

It's just a guess, as the car learns your driving style it should become more accurate over time.  

1 hour ago, TomsFocus said:

as the car learns your driving style it should become more accurate over time

very true.

If you only just got the car the previous driver may have done lots of short trips around town, or had a heavy right foot.

You could of course just clear all readings from the fuel computer/mileage and that will speed up the re-learning process

As above, just clear all the reading to help it learn quicker.

When I bought my MK4.5 the average mpg was 36. I reset everything and once I got used to diesel (from a V6 petrol), the average went up to 42-44mpg in my 2.2 (more like 38-40 now after 8 years)

The fuel tank in a Mondeo isn't particularly large - 60 litres I think? My 2018 Vignale Biturbo diesel does around 46mpg on average - quite a bit less than my old 2005 2.2 TDci but then it's a heavier car and quite a lot more power. I expect you will get around 600 miles on a tank, depending on how you drive and the roads etc.

Wow, I didn't know that. 70 litre tank in the MK4.5...didn't even notice when my friend owned a MK5.

Interestingly the AWD has a 66 litre tank

Once you start driving economically the range does go up as you do a few miles. When I fill up my miles  remaining can be in the 800+ range

in this image i had done 114miles after filing up and still 900 range