jumped in the car yesterday to take it to a garage to trade it in against a van and the sodding thing wouldnt start it was showing 20 mls left in the tank so there was plenty to get to my local garage 5 mls away,rang the garage and they said they be out as soon as they can after 3 hrs of waiting i went to town in my wifes car and got a gallon of diesel, chucked it in and it started, so computers on a car are a load of crap you cant go by them, just another thing to go wrong,

 

Were you parked on a slope?

With such a small amount of fuel in the tank it could easily have all been at the other end of the tank to the outlet.

20 Mile = about half a gallon, that is only about 1/2 an inch deep in the tank.

 

theres a slight slope but hardly anything,when the garage done my manifold i picked the car up and it was showing 5 mls on the computer, had to travel 1 mile to get juice, so when it was reading 20 mile ud think you would be ok