Fuel consumption - XJR vs 4.0 NA
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#2
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I dont think there is much in it
driven gently, it takes a fairly constant amount of fuel to shift a 1.8 tonne car along, and both my 3.2 NA car, and XJR, can achieve about 25 mpg (occasionally 28mpg for the 3.2)
driven enthusiastically, the XJR averages 17-18mpg, and the 3.2 about 21-22
So for a bit more fuel consumption, I think the XJR serves up a lot more performance
driven gently, it takes a fairly constant amount of fuel to shift a 1.8 tonne car along, and both my 3.2 NA car, and XJR, can achieve about 25 mpg (occasionally 28mpg for the 3.2)
driven enthusiastically, the XJR averages 17-18mpg, and the 3.2 about 21-22
So for a bit more fuel consumption, I think the XJR serves up a lot more performance
#3
![Default](/forum/images/icons/icon1.gif)
I dont think there is much in it
driven gently, it takes a fairly constant amount of fuel to shift a 1.8 tonne car along, and both my 3.2 NA car, and XJR, can achieve about 25 mpg (occasionally 28mpg for the 3.2)
driven enthusiastically, the XJR averages 17-18mpg, and the 3.2 about 21-22
So for a bit more fuel consumption, I think the XJR serves up a lot more performance
driven gently, it takes a fairly constant amount of fuel to shift a 1.8 tonne car along, and both my 3.2 NA car, and XJR, can achieve about 25 mpg (occasionally 28mpg for the 3.2)
driven enthusiastically, the XJR averages 17-18mpg, and the 3.2 about 21-22
So for a bit more fuel consumption, I think the XJR serves up a lot more performance
That is imperial (UK) mpg?
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#9
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I've owned all the flavour over the years so here is my take on it.
....taking a look at the UK fuel economy figures and you will never see close to those, the drive cycle for the fuel consumption figures is (and still is!) so easy it was laughable back in the 80's and 90's.
The ECE15.04 drive cycle was used for the emissions test, and fuel economy was generated by the amount of CO2 produced, a very accurate measurement indeed.
Look to the US fuel economy figures for something a little more likely. The drive cycle was a little harder on the but was in many eyes a still a little too favorable.
But you have to have some set standards so you can measure apples with apples, so all this recent bleating in the UK press at the moment regarding unachievable fuel figures can be somewhat misleading.
Anyway enough of the history lesson. Around town in the real world the 3.2 and 4.0, well there isn't much difference although I still feel the 3.2 has it, the XJR (only owned autos) is a little worse...but we are talking cars that are never that great on fuel to start with. Curiously there were some figures derived at Jaguar that proved the auto's were better on fuel than the manuals, some ( I said some!) of which was due to the mismatch of the manuals gearing to the drive cycles used in Europe (all vehicle used the same gearshift points!) and the average Joe to wrongly use a gearbox.
On a cruise, the 3.2 is noticeably better than the 4.0, again the XJR is a little worse...but there is a cavet:-
The XJR....it would be fair to say they encourage some, lets say errrm enthusiastic driving, drive it hard if only to listen to the supercharger on song and then the fuel consumption is gruesome....'71 4 barrel AMC 360 Javelin and C3 Corvette mpg levels come to mind, having owned all at the same time...all good fun though, but at a cost. I always had a feeling that the XJR's fuel mapping runs very much on the rich side when the taps are open, my guess was to inhibit detonation (pinking) issues.
As the man said earlier two fuel pumps and all that horsepower comes at a cost.
but they say, your milage may differ...
....taking a look at the UK fuel economy figures and you will never see close to those, the drive cycle for the fuel consumption figures is (and still is!) so easy it was laughable back in the 80's and 90's.
The ECE15.04 drive cycle was used for the emissions test, and fuel economy was generated by the amount of CO2 produced, a very accurate measurement indeed.
Look to the US fuel economy figures for something a little more likely. The drive cycle was a little harder on the but was in many eyes a still a little too favorable.
But you have to have some set standards so you can measure apples with apples, so all this recent bleating in the UK press at the moment regarding unachievable fuel figures can be somewhat misleading.
Anyway enough of the history lesson. Around town in the real world the 3.2 and 4.0, well there isn't much difference although I still feel the 3.2 has it, the XJR (only owned autos) is a little worse...but we are talking cars that are never that great on fuel to start with. Curiously there were some figures derived at Jaguar that proved the auto's were better on fuel than the manuals, some ( I said some!) of which was due to the mismatch of the manuals gearing to the drive cycles used in Europe (all vehicle used the same gearshift points!) and the average Joe to wrongly use a gearbox.
On a cruise, the 3.2 is noticeably better than the 4.0, again the XJR is a little worse...but there is a cavet:-
The XJR....it would be fair to say they encourage some, lets say errrm enthusiastic driving, drive it hard if only to listen to the supercharger on song and then the fuel consumption is gruesome....'71 4 barrel AMC 360 Javelin and C3 Corvette mpg levels come to mind, having owned all at the same time...all good fun though, but at a cost. I always had a feeling that the XJR's fuel mapping runs very much on the rich side when the taps are open, my guess was to inhibit detonation (pinking) issues.
As the man said earlier two fuel pumps and all that horsepower comes at a cost.
but they say, your milage may differ...
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Last edited by iconic; 03-01-2016 at 01:45 PM.
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