Hi all, hope this is the right place to post.

I've had a MK2 focus for a few years, been generally happy with it. After a long weekend of chores I got home last night with exactly 50 miles left on the trip computer thing.

Not ideal but I had a 25 mile (24.7 to be exact) trip first thing so decided that was fine and I'd just fill it up when I left work as we have a station about a mile away.

Coming off the motorway the mileage was dead on, 22 miles used on a 22 mile stretch. The weird thing is that in the city, at 6am with no traffic and no red lights so no stops, it went from 28 miles left to 9 in the space of 2.7 miles.

I went to the petrol station instead of work as was worried during rush hour at that rate it wouldn't make it, and arrived with still 9 miles left. I sat in the car for 10 minutes until station opened, no engine running. When I turned it back on, the trip computer showed 0 miles remaining.

This may seem stupid to ask, as I know these things are very inaccurate but this seems extreme even so. My MPG is supposedly 40.1 which as I work in the city and live in the countryside I'm happy with.

Could I have an engine fault? Or a brake fault? I've felt nothing like a sticky brake, or is this just normal and I should completely ignore it? It feels like the fuel usage backs it up.

Not a fan of doubling my mileage 😂.

Its just normal when your tank gets low the fuel remaing mileage is vague to say the least, not to bad if you keep driving but goes all over the place if you stop 

different brand car but the stupid range display turns off with 40 miles to go and only displays a red fuel pump....

I asked if they can kill this and leave the display to empty reading which is very useful (rather than something utterly useless...) they can't, but they did turn on a previously hidden digital "tank fill level" reading I can scroll too.  But it wobbles about more than you'd expect.... 

the other day the separate low level light had been on for a few miles, so I toggled to tank level whilst driving on a smooth flat road at a constant speed to find it reading 0.0 gallons... thinking opps better drive slowly to a fuel station, went round a corner up and down a small slope back on the flat at constant speed I now had 0.9 gallons which shortly went up to 1.0 gallon....