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Discussion Starter #1
Does anyone know how the XF calculates the range of the fuel left in the tank?

I took delivery of my three-litre diesel last week and immediately set off for a 50 mile drive. I then (almost) filled the tank up and was given a "range" of 488 miles. I then set off on a 240 mile commute (doing 39.5 mpg for the trip) and now I've got 130 miles left in the tank.

Seeing as I'm already running near the limits of the XF's 42 mpg on day one, how can the range be over 100 miles 'out' after one run? I was hoping to get two commutes out of a full tank, but it looks like I'll have to settle for one and a half tops.
 

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You may need to look again after you have covered a few more miles. I do remember that after "zeroing" the trip meter and then travelling 30 miles on a good flat road without any drama and so on, the meter displayed a consumption figure of 45mpg :lol:
At that time the range, whatever was showing, would have been based on that very artificial consumption figure and no doubt would have made me very happy :D Do the same distance in different and adverse conditions, all will have changed and I would , no doubt be sad. :(
 

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Hi Rich,
I think, in reality, you'll find your mpg is sadly not as good as the trip might suggest. I have never got anywhere close to 40 mpg and average around 30 (by my own calculations) whereas the trip suggests I'm closer to 34.

Goodness knows where Jaguar get the 'mythical' 42 mpg from - on a rolling road at a steady 56 I guess :( which bears zero resemblance to real life driving. Just enjoy the car and the looks you get from other envious drivers when you fill up :D :D :D
 

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XFAndy said:
Hi Rich,
I think, in reality, you'll find your mpg is sadly not as good as the trip might suggest. I have never got anywhere close to 40 mpg and average around 30 (by my own calculations) whereas the trip suggests I'm closer to 34.

Goodness knows where Jaguar get the 'mythical' 42 mpg from - on a rolling road at a steady 56 I guess :( which bears zero resemblance to real life driving. Just enjoy the car and the looks you get from other envious drivers when you fill up :D :D :D
Andy,
I went to a lot of trouble to provide an answer to that here:
viewtopic.php?f=26&t=899
 

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Discussion Starter #5
Thanks for the replies. It was a 240 mile trip, of which 230 miles were on the motorway so I was expecting 33-35 mpg economy. I reset all the trip settings prior to the journey so I was pleasantly surprised by the (alleged) mpg but not by the amount of fuel supposedly left in the tank!

I was hoping a 15.3 gallon tank would allow me to do 500 miles (which is around the 33 mpg mark) of motorway driving.
 

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Thanks pekem for the link to the explanation - I hadn't previously seen that :oops:
 

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Hi,

The range figure is 'dynamic' i.e. it more reflects real time average.

For example, when you set off range may be x miles but as you continue and engine warms up etc. range can significantly increase (calculation reflecting current mpg)...put your 'boot' down and range decreases etc.

Only way to get accurate mpg, imo, is to 'brim' run and brim again. I found that over 32,000 miles in my ML average mpg was 27.4 mpg v manufacturer combined of 30 i.e. approx 10% less in 'real' world (v artificial government testing world).

So I would expect over a reasonable period mpg to approach 38....I'll let you know this time next year what mpg I achieved (awaiting 3.0 'S').

Cheers,

dieter
 
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