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Tank capacity, Fuel Gauge & fuel consumption.


Laffer
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Yo all - I need your combined wisdom yet again.....

What is the tank capacity of a pre facelift S8? I am sure I read somewhere 90 litres but with fuel gauge below red I can only get around 76 in!

The fuel guage seems accurate until about a third of a tank left when it seems to do it's own thing..... as in, sometimes I have a third (maybe a qyuarter) of a tank left when switching off the engine, then coming back to the car a few hours later the gauge will be in the red, after about 10 mins of driving the guage settles out to where it'should' be.

Lastly fuel consumtion seems more dire than I had imagined. One full tank will get me between 300 and 320 miles. I have not worked that out manually but the trip computer is calculating that average to be around about 18 to 21 mpg. What are you all getting out of your 4.2's? I expected to get mid 20's and was hoping for late 20's - looks like that may have been wishful thinking and a case of heart ruling head big time in my purchase decision.

BTW my work run involves little queing - Main A road and then Motorway.

Any feedback, appreciated (as usual)

Laffer.

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Tank is also 90 liter imho. But check RSModels for an online brochure.

The 14 liter 'reserve' doesn't seem that strange. They tend to keep on the safe side with gauge and DIS -> miles left indication. (Why not use that, may be more convenient?).

I usually get ~ 550 km out of a tank. But I don't let it go into the red. Again, the DIS should give you an indication for mileage. Seems yours uses a tad more.

Gauge: maybe the fuel gauge sender is a bit slow to react. It's a floating cylinder, so it could be hindered by something. You might be able to check/service it via the trunk/boot. (Audi says "special tool", but that's what they usually say). May be wise to disconnect the battery first (think radio code).

HTH

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The 'miles left' or range function seems to calculate from from the fuel gauge sender and the current MPG (not the historical one) as you can make it vary wildly by changing your driving style. The last time I filled from empty the range was reading 10 miles and the fuel gauge was right at the bottom of the red - still only got 77 litres in her though.

I suppose the only real way to test is run her dry with some extra fuel in the boot for when I run out. But I hate running cars dry - I always think some damage is going to be done (although with all the filtering that happens, this is unlikely).

The reason I mention all this is because I do over 500 miles a week. Currently my fuel bill is over £500 a month - that is a huge chunk o cash (the Golf TDi 130 is starting to sound extremely attractive!!). Needless to say I pay for my own fuel (unfortunately).

I'll see how it goes and try to drive with a velvet foot for most of the time (although sort of defeats the object of owning such a car in the first place).

Laffer.

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I do about 250 miles a week - 6 miles heavy traffic and 22 miles motorway each way - I get a steady 21-23 indicating on the dash although when I did several fill up to fill up calculations I found milage was a little worse than this by about 2 MPG. I think the true figure is 18-21mpg....

I think the manual says it is a 92 lite tank - often when the "running low" display comes on there can still be over 25 litres still in there (especially if the car is parked facing down hill.)

Initially its thirst used to bother me but now I try not to think about it. (My missus calls my car 'Global Warming'). Steady driving and not going bananas on the motorway does help as does the ECON button on the Aircon. In the end its how much you want to deprive yourself of the pleasures of the car in order to save money.... For what it is, the A8 is very economical (go drive a V8 Jag or a big 4 x 4 and see if you get 20+ MPG !!!)

Another good way to reduce your fuel bills is to make sure your wife/partner drives the most economical, cheap to insure car there is...Mine went from a 2.0 ltr Vectra (26mpg) to a Honda Jazz (48mpg) ...a sort of ecomony by proxy if you like..... You have to justify a 4.2 Litre V8 somehow don't you ?

Hey, its a big car and 300BHP (or in your case 340BHP) has to come from somewhere....!!!!

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Laffer, my beast is also very thirsty.22-23 mpg on motorway and as low as 10.2 mpg driving round watford. This is greatly contributed by tha fact that i can,t drive more than 50 meters without finding a fuc*ing speed hump!

I did not think it would be as bad as that around town, but , i did not buy the car for fuel economy so bol*ocks to it! Enjoy beerchug.gif

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The fill up is definately 90 litres, I ran out a couple of months ago (too much right foot when the computer said I had 15 miles left !!), just over 80 quid at the time to fill her up with Super. The 300-350 miles on a tank sounds reasonable, it has been known for me to drop below the three hundred mark, the price you pay for lots of CC's

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Been away so I've only just seen your post-you don't ned to run the tank dry-fill it right up,trip the milometer to zero,run it for 250 milles or so,and then fill it again-then divide the litres by 4.545,and yuo'll get your m.p.g.-do this 3/4 times and you'll get an accurate reading.I've just done exactly that with mine.and as it happens,the computer was pretty accurate(it showed an overall figure of 15.8.whereas my method showed 15.7!)

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