I took a long trip in my XJ8 and I averaged 24.5 to 25 miles to the gallon. The trick is to keep highway speeds at 70. If you go higher, the mileage slips to around 23

 

Just put 400 miles on the XJR and as normal it was right around 15mpg. I blame it on the hills around here but my trick is to actually enjoy driving the car in a spirited manner which only inlvoves 70mph on the highway when you get stuck behind a Marylander parked in the passing lane. Your mileage is what I typically get with the XK even without limiting my speeds. It must be a hybrid.

 

I've had 500ish miles out of a full tank before today, Lancashire to Dover, then into France. Mostly Motorway driving mind, sitting at 70 mph. Car was a 2001 XJ8 4.0.

 

XJR's get 16 w/ premium.

 

This thread makes me feel better about mine. I average about 17mpg w/ 91 octane and mixed fwy/city

 

I think they're very economical cars all things considered. I can normally coax 30ish mpg (UK Imperial) from mine on the motorway, that's with the climate control on too.

 

Finally got my XJR on the road over the past week and a half, about 120 miles so far, got about 12-13 MPG according to the trip meter but that's the first time it's ever been driven on the road, so all the fuel trims and shifting and everything are still adapting. Not to mention it needs an alignment bad, spark plugs could probably stand to be changed, it's mostly city/low speed roads since I'm dealing with vibration at high speed, it sat a few years with unknown service history before, and so on... Not to mention indulging that 370hp motor a good bit. Hopefully once all those things are addressed and I'm driving mostly highway I can approach that near-20 mpg. We'll see...

 

Don't forget it's a rolling average that updates constantly. Mine's been sitting about 16-17mpg of average over the hills stuff to work, or if I take a slightly different route I can get about 18. Highway, I sit about 20mpg if I drive "normal". If I were to sit right at the 65 limit (NY State), I can actually push what, 22-23 or so? Slightly better when I go south and into a little better gas, and less hills.

I might be able to baby it into another 1mpg around town, but I don't feel like only driving with 1/3 a car

 

Is the the 3.2?

Our hybrids get almost 60mpg ... now have three in our fleet. It amazing how much less fuel we purchase -- and all of it regular.

 

Never saw higher than 18.8 on mine for a tank of gas. Good luck with 20mpg. I think you'll find a unicorn first

 

in my 2001 XJ8 VDP S/C the trip computer B: mode, which has not been reset in many years and many, many thousands of miles displays a somewhat depressing 16.1 avg mpg. I think this is somewhat pessimistic since manually computing the mpg usually yields 17.75 or better; a small price to pay given the pleasure the car provides me!

 

My current XJ is a 3.2 but the car I'm talking about in this thread was a 4.0. I've got a photo somewhere I took of the average mpg to show a friend.

I drove the 3.2 100 miles back home from where I bought it and it used less than a 1/4 tank of fuel. That was before I correctly adjusted the accelerator cable too. It's been on the drive ever since so I'm curious to take her for a long stretch to see how she does.

 

FF1776: your mileage matches what I was getting on my 01 (24 to 25 at highway speeds below 70; less at 80, US gallons). I was getting typically 15.6 around town (21mph avg speed).

 

Most of my miles are around town, country roads or on the highway at 75-80. To get 20mpg on the R would require a very lite foot.

 

I'd be amazed if I actually hit 20, but a consistent 18 would be much more reasonable than my current avg. Maybe I should have saved for an N/A x350 instead..

Now it's too late, and I'm addicted to that supercharger whine.

 

"Who said a V8 can't be economical?"

 

I only measure on the open highway on long trips.
Urban traffic is too miserable to contemplate.

FWIW, 22.5 mpg/us overall if maintaining 75mph including
those "must merge right friggin' now" moments when I
rocket out of a rest stop.

Those numbers are consistent from years of observations.