Oh Oh!

Visited my old (90 a couple of days ago) Aunt in Tarrington, Herefordshire. She is my fathers youngest sister and the only surviving sibling of 10. She was so pleased with herself for living longer than all the others. The closest was Aunt Joan who died 16 days before her 90th.
On leaving, I switched on the ignition (keyless by the way) and the fuel light came up. N.B. The 990 on the display is the tickover revs. On the move it also shows what gear you are in.
It's only 22 miles from Tarrington, to home in Gloucester. I think I have at least 30 miles when that light comes on so I thought I'd crack on and get to Morrisons garage near home.
At the garage it was 21 miles and I cruised in still with fuel.
One day I must go on a long run with my spare fuel canister, which holds a litre, Just run until I run out of fuel and then put the litre in and hope that I can find a garage within about 8 miles. 
'They' reckon the fuel light comes on with 1 gallon in the tank (tank holds 4.5 gallons) and the average MPG is around 35, which equates to 8.1 MP Litre!
https://youtu.be/E4V_iL7NbOg