XJR thirst

[vladman]

Hi guys,

Is 14-15 MPG normal for mostly town driving in my 2000 XJR (and admittedly, as it's still a new car to me, occasional short "spirited" bursts of acceleration)? I know they're thirsty, but this seems a little too thirsty to me...

Also, I don't think I saw more than 22-23mpg on the motorway, when trying to drive as economically as I could.

Thanks.

[Marki]

vladman said:

Hi guys,

Is 14-15 MPG normal for mostly town driving in my 2000 XJR (and admittedly, as it's still a new car to me, occasional short "spirited" bursts of acceleration)? I know they're thirsty, but this seems a little too thirsty to me...

Also, I don't think I saw more than 22-23mpg on the motorway, when trying to drive as economically as I could.

Thanks.

My XKR did about 22-24 on the motorway

[steelej]

Yeah those numbers sound about right, welcome to supercharged V8 ownership

John.

[pzero64]

You selfish so and so.

Self, self, self. Absolutely no care for the environment.








Kidding.

I had a straight six XJR and the 10 mile drive to work usually equalled 16 - 18 mpg.

Seriously thinking about V8 XJR – would the previously mentioned 14 – 15 mpg be about right for short journey/town?

[groomi]

Yep, that's the same figure I've been getting throughout two years of ownership.

If you're concerned by this, may I suggest you never press the 'S' button and hoon down any B-roads as single figures are entirely possible.

[DrDeAtH]

ah, its only petrol... best use the full tank as fast as possible before it goes off..... i heard it only lasts about a couple of days tops.... that 99 octane stuff lasts even less.....

[vladman]

Thanks for the replies guys. It's more the low 20-ies even when driven economically on the motorway that I find a little surprising... Was reading a test of the new Vauxhall VXR8, it's a 6 litre V8 (normally aspirated), but it still manages 31mpg on the motorway... Is it the supercharger that's the cause of our high consumption, or simply 7 years of engine development?

[groomi]

vladman said:

Thanks for the replies guys. It's more the low 20-ies even when driven economically on the motorway that I find a little surprising... Was reading a test of the new Vauxhall VXR8, it's a 6 litre V8 (normally aspirated), but it still manages 31mpg on the motorway... Is it the supercharger that's the cause of our high consumption, or simply 7 years of engine development?

Probably a combination of both and also the fact that our sleek Jags are actually pretty aerodynamically enefficient which will make a difference at motorway speeds.

Still, it could be worse, it could be a Vauxhall...

[DrDeAtH]

the Vauxhall is probably made out of some thin material which would fold in a crash. Our jags however are hewn from materials recycled from old warships, dead cows and trees, and as such make them a tad heavier than a normal car....
Yes, engines have also developed over the years, the straight 6 isnt the most economical, but it is very smooth and powerful, but that engine has been about for nigh on 20 years now with some minor redevlopment. i'm sure the XJR V8 guys would be able to tell you more about the smoothness of their engines....

[xjrmark]

Spot on. About 15mph in town and 24 on the motorway.

[xjrmark]

Forgot to mention it has got quite a bit better since the timing chain tensioners where done. Don't ask me why.

[dnwilliams]

I have a X308 XJR and I average around 17-18mpg for my normal daily commute this involves some town driving and some motorway driving although the M5/M6 interchange is a bit like town driving rather than motorway with 8 miles of stop start, my driving style isn't exactly economic either but it's a supercharged V8 so I make as much use of that as possible , we drove up to Scotland for a weeks holiday a couple of years ago and I averaged 25mpg on the run up the motorway. If you put it in sports mode and nail it though you'll see it drop down to 4mpg

Edited by dnwilliams on Tuesday 10th July 09:00

[Johnniem]

I also had a 6 pot XJR, until recently, and over an ownership spanning six years found the consumption figures were pretty much as you have quoted. Were you expecting much better? It is, after all, a V8 with a 4.2 litre engine. I have recently acquired a 450 TVR Chimaera. Now there's consumption with a capital C. Eco-Armageddon!

Enjoy the XJR, it is a truly fantastic machine!!

[vladman]

I think some people who responded may have gotten confused over which model of the car I have. It's a 4 litre supercharged V8 (x308), not the newer 4.2 litre, or the earlier 6-pot one...

[xjrmark]

Vladman, I am also driving a 4 litre V8 XJR of about the same age. I think the newer ones are 4.2. My fuel consumption is identical. I don't know what you were driving before but the mpg figures can be a bit of a shock at first, 390 bhp doesn't come free. My first Jag was a 4.2 litre series 3 saloon which was really bad, about 9mpg in urban traffic and 20mpg on a run if I was lucky. It turned in 200 bhp so it just goes to show how much more efficient the modern V8 is, but don't expect anything better than you are getting.

[groomi]

Just thought I'd add to this thread that a minor miracle happened yesterday. I managed to average 24mpg over a 150m round trip - a new record for me, despite some periods of heavy traffic on the M25 and rushing for a meeting.

No idea how I managed to beat my old record of 23.5mpg considering that was set by driving like a fairy.

[jas xjr]

i have a 1999 xjr v8. i have tried on a run from stoke to london to get the highest mpg,just as an experiment. could not beat 21mpg,drove like my grandad.
still we didnt buy them for the fuel consumption did we?

[Job38]

I used to get a cobmined average of 19mpg.

Positively frugal compared with the 10mpg I'm getting from a 6.3L V12

[Big Rumbly]

Ive had my 97 xjr 5 months now, overall I'm getting about 19 MPG, can creep up to 23 on a run, but Ive stopped using the tripmeter now, just put petrol in when it needs it, stops you worrying about the price.