Is the fuel tank ' \/ ' shaped? For some reason i can drive 100 miles or so an the needle will barely move, but the further I drive the quicker it seems to drop. By half a tank the fuel seems to plummet through no change in my driving style. Am I just seeing things or has anyone else noticed this?

My pre FL octy did this and so does my FL one. I find the first quarter of a tank lasts around 220 miles or so. Then the next 2 quarters give around 100-150miles with the last quarter being around 100-120miles.

This seems to be a trait of a lot of cars... Almost every car I've driven in the last 15 years has behaved like this so some extent, with some being worse than others

This seems to be a trait of a lot of cars... Almost every car I've driven in the last 15 years has behaved like this so some extent, with some being worse than others

+1. There must be a scientific/logical reason for this. Would anyone with more technical nouse than me care to offer an explanation for why the fuel gauges on the many cars I've driven over the past 30 years indicate half a tank has been used, when 2/3 of a tank used would be closer to reality? You'd think such inaccuracy would be a thing of the past.

I wondered if it had anything to do with extended test drives? Someone takes the car out for 24 hours and does 100 miles in and thinks that the car is so fuel efficient it uses very little fuel? A wild & unfounded conclusion, but its all I can think of.

I can quite easily do 75 miles an it still looks like I have more or less a full tank, then the more I use the quicker it drops!

Yup. If I brim the car the needle won't move for 60 miles but then will drop 1/4 per 100 miles as would be expected.

I always try to top up with around 1/4 of a tank left. It also makes me feel like I'm not using as much petrol as I really am.

Filling a tank from empty is frankly too frightening these days.

Surely this is just down to the fact that when you have fully brimmed tank you also have filled up all the pipe work etc get the fuel in the tank?

Brimming the tank will no doubt move the fuel past the top of the range of movement of the level arm and so it will look full until it's past this.

Lets face it, the arm can't go past the top of the tank, so at some point it's going to have fuel going past it's upper limit.