Hello,

I have an '04' XJR and I have been getting great mileage on the highway but in all city driving I am barely getting 12 MPG. Just recently had the 45K service completed and still not able to get even close to 17 MPG. I'm not the run and gun type although I do beat an occasional red light. I also am not using the sport mode. When using INST Fuel view it is usually around 5 - 8 MPG from light to light and it never makes it above 15 MPG unless I am completely off of the gas pedal (coasting). Could there be something else wrong or was Jag way off the mark claiming 17 MPG City

What are others with XJR's getting as far as city driving is concerned?

Thanks,
Robert

 

Well I drive really hard, my car has the same engine, its HEAVIER, and I get around 14 city with sport on.. When I drive it nice I can usually get 16-18.. And on the highway I can get around 25-27 so 12 sounds veryyy low..

Is this actual like the miles you drive on the trip odometer divided by the amount of gas you fill up with?
Or are you using the one on the dash? (its very inaccurate)
Do they replace your fuel filter at 45k?
Are your spark plugs original?
New air filter?
Have you ever had your injectors cleaned?

Eric

 

Do you have an anchor dragging behind your car??

 

Good thoughts from Eric. I have a long wheelbase XJR (super V8). I get around 16-17 mpg for city driving. But, what is city driving? To me, its my around town and daily commute. That includes some highway miles, but during commute hours, its pretty slow. Average speed is actually an important part of interpreting your mileage, IMHO. I amd typically averaging (based on the trip computer) around 25 mph during these city driving periods. if you are substantially below that (lots of stop and go, slow streets with a lot of stop signs or lights) then you mileage will suffer.

While I know that the trip computer may be innaccurate, I have compared what it says my mileage is with calcualted mileage after a fill up. Usually 1 mpg difference. Never more than 3. And it can be above or below the true (if that is the term for miles devidied by fillup) mpg. I think the error in the true value is influenced by the point at which the gas nozzle decides my tank is full. No way to tell how true that is and I never try to squeeze in the last couple of drops.

At any rate, 12 seem low to me, unless your city driving is very slow with lots of stops.

 

Hello all,
Thanks for the info. My daily driving is extremely slow because I live in downtown Washington, DC. It is basically red light to red light and I never really get above 15 MPH when going most places. I figured that was the culprit considering I am getting 21+MPG on the highway.

Thanks for the help.
Rob

 

In my XJR i have never determined my gas mileage in the city its kinda of a waist of time in my opinion. Now on the hi-way i get 27-29 miles per gallon @ 65-70 mph (per onboard computer). But keep in mind i have a new fuel filter and also a new K&N filter fresh oil change, spare tire and jack removed and all the tires are set perfect at 32psi.