Is there any difference? I can't find any figures.

I've been told the 4.0 is actually more efficient...

 

I've heard the same but never confirmed it. The theory is that you have to flog the 3.2 a bit to get any oooomph and actually end up using use more gas.

If you're a gentle driver, though, and don't mind being at the end of the pack rather the the head of the pack, I gotta think the 3.2 would be easier of gas.

Cheers
DD

 

I've had 23mp(imperial)g on the xjr and that was on the motorway. I've also had 17mpg and 27 mpg and these were all calculated by myself with brim to brim fillings. The last time I had it out I got 26.5 on the trip computer at steady 60mpg with 5 people in the car (well chuffed with that one).
The 3.2 Sport read 26 maybe 27 mpg and that was my commute which is mixed roads and a mixture of driving styles. These figures were taken from the trip computer.
There are many variables that come into play with mpg.
I have to say that I was not dissappointed with the 3.2. If it is only yourself in the car and taking into account national speed limits, then I don't think there's too much of a difference. You've got the quicker gearbox and diff in the 3.2. That said I never really got confident about overtaking in that 30-70mph band.
I've no experience of the 4.0 NA car though.

 

quicker gearbox and diff just means lower fuel economy without even pushing the car, the longer diff ratio helps on the 4.0l na cars on the motorway fuel economy.

Dont see the point of a 3.2 tbh its not like any of us are looking for fuel economy and the 4.0 na is only 70hp down from the supercharged model so its really not slow. I dont drive that lightly on fuel consumption and always manage 18-25 100% stop start town driving.

 

The point of the 3.2 is that I couldn't find a single 4.0 at the time. Even today you're lucky to see one 4.0 for every ten 3.2L x300s on the market over here.

I don't know why they're so rare in NZ.

Never found the 3.2 underpowered though...

 

The 3.2's are underpowered I have had faster MPV's no offence intended but its meant for comfort and cruising and on that end it wins hands down.

The 4.0l sports are very rare over here as well took me a while to find one even managed to find a manual one but the owner wanted silly money for the car.

 

my 96 xj6 is between 21 and 22mpg commuting with 70% freeway and 30% city road.
100% freeway is between 23 and 24mpg but I can't get more than that.
Anyone meet similar numbers ?

 

I had both versions, 3.2 for 3 years, currently driving 4.0l LWB which is heavier so using slightly more fuel than standard I suppose and the 4l is still slightly more efficient I think but its barely noticeable, maybe an extra mile per gallon with the 4l engine and I'm doing 10k miles a year in it.
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I did drive the 3.2l in a more spirited way I suppose too even though 4.0l is definitely a quicker car so that is probably a reason for a slightly higher fuel consumption.

 

Official UK consumption figures, in imperial mpg for automatic transmission versions.Urban: 19.8 19.8
56 mph: 37.7 36.7
75 mph: 31.0 29.1

With my 4.0 I have been able to achieve 35 mpg with mixed driving between 55 and 70 mph, and that's after a change from 3.58 differential to 3.77.