Having owned my new-to-me 2012 XK for a couple months, I find that the fuel economy is miserable at 10.6 mpg (this is largely city driving and maybe 30 miles a week). I don't expect great fuel economy, but this seems too low for a car of this age and technology. I also think the transmission is "lazy"... Whether in sport or normal settings, it seems to bog down... long hesitation before down-shifting... Other than that, it runs perfectly. I have yet to buy a code-reader to see if it has any codes, but with this low mileage, I would not suspect anything is in need of replacement or cleaning. Any ideas? Thanks

 

What is the mileage ? yes correct should be at least 16 mpg or more

 

Seaice! Welcome!

Be sure to head over to the regional section and say "Hi!" to the locals in the Pacific Northwest!
Also consider putting your car info in your signature section (found in your user control panel).

My 2010 XKR averages about 16 around town, so if your getting 10.6 of a base XK, then I have to think something is wrong. Do get a code reader on it to start, and as George05 asks, how many miles on her?

Was she always a local car or did she come from out of state?

Peace!

 

Start with an OBD tool and read fuel trims, after checking it's running CL (closed loop).

It may not be running perfectly, just appearing to do so...

 

This will be interesting to see how this shakes out as your investigation goes forward. As suggested above, a code reader ought to be your first step. In the end though, it may be an effect of more than one issue, i.e. air filters, fouled valves, etc.
You may wish to research some threads here on somewhat similar performance issues where cleaners and additives are discussed.
Do keep us posted on your findings.

 

My guess is stuck thermostat.
Check to see what the temperature is after 5 minutes of driving.

 

The mileage is only 19K, though the car is 8 years old so certainly that could be a factor. I haven't started pulling things apart, engine bay looks new. It runs so well, and there's no smoke, no smell of unburnt fuel, or soot in the exhaust, it seems to be very clean running. Is there a good code reader and app available?

 

a must buy if you plan on keeping the car i have one good bit of kit to have

 

Are you quoting true fuel consumption by calculation from fuel added and miles travelled or just from the vehicle message centre readout?

I think it was you who mentioned elsewhere the vehicle was previously owned by an 80 year old with a habit of hitting the edge of the driver's door on his garage wall.......? If so, perhaps he was also not one to investigate the performance potential.

I expect a hard reset to put the fuel trims etc back to default followed by an Italian Tune Up will resolve the sluggish performance. The transmission has learned adaptions and would otherwise eventually adapt to your driving style.

Graham

 

10.6 US is about 12.7 UK. But still on the low side, unless you are in stop go/crawl traffic, when it is quite possible. Do a gentle trip into the countryside and see what the best you can do. That will give you a much better idea of how well or badly the car is doing. If you get somewhere near book values on a gentle cruise, nothing is wrong with the engine. A hard reset, or some repeated hard acceleration will speed up the relearning process. Citty traffic is really difficult to predict and a 5 litre engine idling or accelerating uses a lot of fuel and so I try and avoid town trips with mine

 

We can be all but certain that this car sat a lot. Drain and clean fuel tank, replace fuel filter, put a good cleaner with PEA into fuel tank and drive it like you stole it.

 

Oh horrors. It likely is indeed.

Change all fluids, use OBD after that.

 

Local car, owned by a former mayor of Seattle in the 1970s. I do plan on reading the codes first. looking for the right code reader, probably the LRII. Thanks

 

I'm just relying on the vehicle information center, I've run a couple tanks of gas through the car with cleaners, reset the meter, mileage is fairly consistent. It has been driven in the city/suburbs, not heavy traffic, but not highway. I'll have to say I'm deep into the accelerator most of the time, and almost exclusively in sport + Dynamic mode. Nonetheless, I would have expected about 15 mpg city, maybe 22-26 hwy (using my past cars of this performance level and technology as a basis). I can live with the mileage, I just find it curious that it runs so good and cleanly that mileage isn't better. I will do a hard reset shortly, and a code reader to see if anything pops up. In the meantime, I love the car, particularly the ride... Roads in Seattle are truly poor and this is by far the best riding performance car I've driven here.

 

The path of a public servant is such an arduous one.

 

Thanks all for your input. First thing on my list to do this weekend is check the throttle body for any deposits and do a hard reset to allow the vehicle to relearn my driving style. Then get a code reader (the iCarsoft LRII) to check the codes. The condition of the fuel system for such a low-mileage car is suspect, O2 sensors, TPS sensor, Mass Airflow... etc. all warrant looking at.

 

In my humble opinion Graham has hit the nail on the head

 

I've been meaning to comment on this elsewhere: as with any big 8-cylinder engine, mileage can vary wildly. (I don't care how you drive, there's only so much fuel you can spray into a 1.8 liter 4-banger.)
My XKR is my daily driver and I have the worst possible commute: about 4 miles each way, about 20 stop signs and red lights, and I never get above 40. Plus, with LA drivers being how they are, I sometimes have to, well, "make a point" if someone's too aggressive on Wilshire Blvd. So, yes, I floor it. I try to balance it out with longer weekend trips.
My normal combined is 14.6. Seems about right for what I do.
BUT: I took two mileage readings on a cross-country drive: WEST of the mississippi I got about 18mpg. EAST of the mississippy I was up over 21 mpg.
My guess: west of the river I spent much of my time over 90mph and I'm guessing the air resistance was killing me. Between traffic and speed limits, I'm between 60-80 east of the mississippi. Yeah your mpg is low, but it's not awful, my opinion.
And yeah your transmission kickdown will improve with a lot of aggressive driving. Learn to love the paddle shifters and get a feel for where you want the car to shift.

 

that's what happens when you buy a base model lol the tune is wayy off and it's low powered as can be.Me on the other hand,I beg to differ cause every Jag I ever owned always been atleast the XKR model.I never waste my money buying a car that just looks fast and don't have the speed and power to back it up.Might as well not waste your money and keep saving up so you can buy the REAL thing might as well say

 

Very mature Barry what are we in high school ????