If you want to have a look at some of the maths then these Formula One websites might help

http://f1datajunkie.blogspot.com/2011/05/f1-2011-turkey-race-fuel-corrected.html

http://www.gtplanet.net/forum/showthread.php?t=66359

http://www.f1scarlet.com/f1_beginners.html

Not so much MPG v Fuel Weight but performance v Fuel Weight, with the difference being close to 4.5 seconds per lap as the tank empties during a race.

The other thing you may notice (I have in some cars) is the handling as the fuel tank gets lighter. If you consider a 40 litre tank is about 30kg of weight and that will change the centre of gravity of the car as will the number and position of passengers.

nice photos!

Economy, now we are talking my language.

I filled mine to the very very brim, and got 150-160 miles untill the gauge read 3/4's full. (1/4 tank and a bit I'm assuming)

I find up gradient or down gradient/ clear roads to make more of a differnce than the fuel amount, or passengers. amount of take-offs do in the ecomomy

I'm always trying to see the best that I can get the average to say, certainly I get no less than 55.6mpg, sometimes I swear that's hard wired.

I'm finding I'm switching off at near every red light.

If I'm getting 60-62mpg then I feel pretty smug, and that usually if the roads are completely clear.

600Miles out of a tank is good in my book, and mine's the estate fabia (which I think looks like a mini old merc from the rear)

All round my fabia has been the best car I've had.

My mates go on about performance, but my fabia is fast enough to be fun, good looking enough to be interesting (better than the fabia II IMO), comfortable enough to be relaxing and ecomical enough to be impressive.

BTW, if you're interested, finally got round to removing the rear seats and parcel shelf last night (never use them: seats have been in the folded foward position for about 2 months beforehand). Weighed the seats before tucking away in the loft: LH & RH bases and backs came to 27.5Kg. That's almost the weight of the fuel in a full tank, so now I'm going to not worry about brimming when filling. Before that I was finding that going to work (slightly uphill and in a rush/traffic) I got 52MPG and going home (slightly downhill and little more leisurely) I got 60-63MPG. Although it's mostly to do with driving style, I'm hoping the reduction may make it a little easier to maintain or improve those figures. With 150mile round-trip everyday I need all the help I can get!

Weight of 27 litres of fuel is the reason I half fill.

Diesel weighs approx 0.85kg/l

So 27 litres weighs 23Kg

Positive it makes a difference.

Edited 31 May, 201115 yr by prolfe

I got 71.8mpg the other day, I still can't believe it! it was 3 am, averaging 28mph, it was up and downhill.

I even took a photo of it cos I thought I was dreaming.