When my fuel guage is showing half full the mileage covered since filling up is generally showing around 250/270 miles, so naturally I'm assuming it's going to reach 500 or so miles when it reaches the red. Rather annoyingly however I'm generally just 400/420 miles when it reaches red, so can anyone explain where the other 100 miles has gone. Does it just leave you plenty extra left in the tank to save you running out?

If I use the estimated mileage left in the tank reading on the MFA it's even more exaggerated.

Most fuel gauges are not 100%

First half takes ages to fall the the last half falls very quickly in comparison

its kinda like 1/2= 2/3 of a tank and the last half= a 1/3 or a tank

I expect the bottom of the tank is slightly smaller than the top half, probaly how they get it in the chassis.

mine dives like that

Yep, mine is the same, as have been other cars I have owned over the years, just one of those fuel tank shape things I reckon! And yes the last 150 miles on the trip comp go fast!

I expect the bottom of the tank is slightly smaller than the top half, probaly how they get it in the chassis.

mine dives like that

how can one half of the tank be smaller than the other half...

how can one half of the tank be smaller than the other half...

Because we drive Skoda's!

To the original poster - Yes, my car does it too! I normally dont look at the fuel gauge or trip at all. But every now and then i challenge myself to get what the trip says i can get from a full tank . . . So annoying when you think your on course half way though!

Ive never got close!

how can one half of the tank be smaller than the other half...

Could be like this - Trapezium | Giraffian

400 is good I normally get 350 2 a tank

Yeah I notice that but I'm currently on about 400 miles at the moment on the last bar before red, I guess it depends on the driving enviroment as on my trip down south last week I managed to get 478 miles out of the tank before the fuel light came on and I think at a push I could have got 500 miles out of it, I think I'm going to be lucky to get 420 -430 before filling up next time!

yep me too.

after 100 miles on the trip I've usually used around 1/4 tank.

that said. If im heavy with my right foot it will drop very fast, but will rise once i change my driving style

how can one half of the tank be smaller than the other half...

Think of it more as a level gauge. Tank could be 50 cm's tall, but if it's wider at the top than it is at the bottom then the upper half of the tank has a greater capacity than the lower half.

Me too. In fact the needle takes ages to even move off max when I have filled it completely. Then the lower "half" seems to go much quicker than the first "half".

You should count yourself lucky your not driving something French! My old Citroen ZX Volcane's fuel gauge used to move around like it was a pendulum, all you could really use it for was to determine if there was fuel in the tank or not.

If I've filled the car to the brim, I've noticed on average the gauge won't move off full until 200 miles, will be on half around 400 miles and empty by 600.

So I've assumed the actual guage covers 37-40 litres of fuel and at the beginning it doesn't change because I'm burning off the reserve of 5-7 litres and what I've managed to squeeze into the filler pipe

You should count yourself lucky your not driving something French! My old Citroen ZX Volcane's fuel gauge used to move around like it was a pendulum, all you could really use it for was to determine if there was fuel in the tank or not.

Agreed Bloody things were like they were made of elastic bands

Oh well glad to see I'm not the only one.

What I meant was the tank may not be a complete rectangle or square when fitted, I don't know, I have never seen one out, but there is nothing stopping them having an out of shape tank, providing the fuel guage is callibrated accordingly.

I had 400 miles at half tank, but only managed 675 before the light came on ... 40 litres to fill to the brim

Is it not that when you fill it right up, theres about 50-100 miles worth in the filler pipe? So you get an extra so many miles out the first half.

Not often im smart, but me thinks thats what it is. . .

I had 400 miles at half tank, but only managed 675 before the light came on ... 40 litres to fill to the brim

That's around 77mpg for the entire tank! Were you driving downhill for the entire tank?!

mines exactly the same.

when brimmed the needle doesnt move untill 80 miles in. from there both halves of the tank holds 200miles worth.

making almost 500 miles. the rest you blow on starting, pulling away, accelerating etc as thats far from economical.

im usually around 430odd to a tank.

thats how iv always looked at it anyway!

what i dont understand is when companies quote an average urban MPG which is usually higher than the others. whenever im in town i struggle with 40mpg! outside town its 50's and briefly 60's

same here with an octy, first 80 miles doesnt move then three quarts ive done 150 miles then 220 by half way, 300 by three quarts and about 400-420 for empty section.

That's around 77mpg for the entire tank! Were you driving downhill for the entire tank?!

I practice the art of 'momentumism' ... once the speed has gathered (sdi - glacial acceleration) I don't slow down ... for anything!