As an experiment I have been following a few guidelines with my last tank of RON95 petrol:

I managed to travel (mainly rush hour commuting up the M3/M25) 426.9 miles on one tank of fuel taking 56.95 litres to refill it to the same point. This equates to 7.496 miles per litre; 34.077 miles per UK gallon; 28.372 miles per US gallon.. The fuel warning light came on at 370.3 miles.

Needless to say, I'm pretty impressed with the economy I achieved.

I will repeat the experiment with RON98 next month to see if it make a difference, and justifies the extra 7p per litre.

I would be interested to hear if anyone has travelled further than 426.9 miles between refills.

 

Hi Bob,

I am impressed! I filled my up yesterday and zero the counter! I am driving normally. I.e. fast and very fast.

Lets se what I get!!!!


JB

 

I have been getting between 26 - 28 mpg (US gallons) mostly highway with some city

 

my M25 run gets me between 26 - 28 daily on a clear run I manage 30+

 

I get a tad over 20mpg. Not much highway driving. Would get better gas mileage if i didnt have to rev it so hard to get moving :lol:

 

With an Upsolute mod I'm getting:
28 MPG lots of stop and go and a few 100+ runs
34 MPG normal going to work type driving
36 MPG very conservative driving, (short test run)

Basically I average about 30-33 MPG.

I'll have to check range per tank next.

Matt

 

RGT,
Do you have a manual trans? Seems like a lot of miles.
I wonder how much difference there is between the manual and the auto?

 

Auto.

When Gary did my chip mod he said I'd get better mileage, he wasn't kidding!

As I've said before, I'm more impressed with the mileage increase than the extra ponies!

Matt

 

Very interesting......

I have been very, very, **** about my MPG montoring, and I simpy find it hard to believe that anyone can get over 28mpg when averaging 80-100mph on a freeway, shifting close to 4000 rpm, and actually exceeding 100mph twice.

The only reason I say this is from my own experience. I have been calculatiing my mpg religiously since day one. I am VERY **** on how I have been calculating the MPG of my xfire. I now have 8000 miles on it.

I have added the mpg pics to my gallery.

My experience shows that when driving 60-80 mph (95% of my driving is on freeways after rush hour) and shifting at 2500-3000 rpm, it is almost impossible to attain over 25 mpg. The downside to my MPG is that my air conditioning is running 100% of the time (you have to in Phoenix), and the outside air temp is always above 100F, but both of these may only impact about 1 or 1.5 avg mpg. Also, I use the highest available octane here in Phoenix, which is 91.

I ran mine completely (accidentally) out of gas once, and got to 392 miles, and that was seriously babying it the last 50 miles or so. That tank averaged out to just a bit over 24mpg.

I have a manual and I know the MPG numbers are supposed to be better on the auto (which I find impossible to understand-this must be a typo somehere in the DC literature that got propagated), but how anyone can average over 30mpg (RGT stated he does) is beyond me.

My data even includes the MPG I achieved on a trip down from a higher elevation, 6000 feet in Flagstaff to 1100 feet here in Phoenix, and I still only averaged a bit under 26 on that tank (and I started that MPG test AFTER I got up to 6000 feet :wink. And I tried to get my MPG up on that one by driving conservatively!

What in the world is going on here? Bullseye stated he got a tad over 20, and that one makes sense. How many others are getting so much more than I is unknown to me at this time. :?:

As you can see from my chart, my xfire was averaging 21-22 mpg when new, and now that the engine is broken in and I have added the K&N air filters, I am averaging around 24.

Anyone else have some hard numbers?

 

I am also very **** about my fuel economy. You have to be when it costs so much over here. I have fuel records for all my cars from 1984 and I have done over 350,000 miles in the past 20 years (MS-Excel can be a wonderful tool).

When I boot the XF, I get between 290 and 310 miles per tank. I was driving economically as an experiment to see how far I could get on my last tank, and I was extremely surprised to get 426 miles. I have calibrated my speedo, tripometer, and odometer and they are basically accurate.

I have the Upsolute Chip and we are near to sea level in the UK. I did not need the air-con much during my experiment.

Anyway, I am going to repeat it in September using 98RON fuel to see if there is a difference.

It is much more fun to boot it!!!! It seems that hard acceleration is where the fuel gets burned the quickest.

 

I'm flat out getting more than 240 miles from tank. Over the weekend, I did actually managed to get 180 miles from half a tank sitting on precisely 100kmh (62mph) in Germany on the motorway - had a friend behind me driving on a space saver. :-(

US Gallons: 15 mpg to 23 mpg

UK Gallons: 18 mpg to 27 mpg

 

Caned a tank in 192miles last week

Dont think I'll be trying MPG experiments !

 

You don't want to know about my fuel economy whilst racing around the Nurbugring over the weekend.

I nearly cried. Best measured in "Gallons per Lap".

There's only one petrol station there and they must make the most money of any country station in Germany. A constant flow of supercars queued up for a tank.

 

Scotth_uk, how do your car do compared to other on the track. What make and models did you beat (if you where racing)

Just wanting to know how the xf holds it's own to others.

 

Are you guys kidding???? I can't do better than 320 miles on a tank of gas

 

I know I get over 20 mpg,but since I had a honda Insight that got 60-70 mpg and it didn't really save any real $$s I don't really care. MY XJ12 6.0 gets maybe 12-17mpg but it hauls *** and I love driving it.So as I love driving my XF and don't care about MPGs.

 

Pereze333.

I'm deadly serious with my figures, and they will be quite accurate.

On my current tank, I'm booting it somewhat so I expect to get around 320 miles before a refill.

Am off on a long run tomorrow, so I'll see the difference over commuting to work.

 

>Scotth_uk, how do your car do compared to other on the track. What make and models did you beat (if you where racing) Just wanting to know how the xf holds it's own to others.

You can never really tell at the Ring, as you don't know if other people are pushing it or not. Given that it was wet, people were taking it easy. No actualy racing there either - it's a "Tourist Drive".

Was desperately looking for the 350Z's in the car park when the track dried out for a run, but no luck.

Spent all day being beaten senseless by the 20+ Porsches in attendance 964's right up to 996 GT3 RS's.

 

My first tank (slushbox don't forget):

Fuel light 312, filled up at 327, 27.61 miles/Imp gal.

Hmm.. C minus, could do better
A

 

Pelked1,
AC?!? I've been using the heater!
Seriously, most of my driving has been done in the very early morning,4-5 am, and it has been a pretty cold summer. I'd say the avg. morning temp is in the mid to high 60's. (Between 42 and 74)

So, in the name of science, I made the great sacrifice of going on a long scenic "sunday drive" on a nice hot (for here) sunny day. No AC, but I did have the windows down. The temp was 82-83F.

Big change! I got 26.6 MPG! I was expecting a loss, not that much though! No flooring it or high speeds, just a leasurly drive.

I'm thinkin' if you want the best mileage you'll have to move to the frigid north, turn off the AC and not have any fun driving. And get a chip mod but don't use that gas pedal!
On the plus side, I do feel the car has more power on those chilly morning drives!

Matt
P.S. I never use less than 93 octane.