Hello Jaguar fans!

I own a 98 XJ8 with about 94k miles. Recently paying attention to the electronic gadgets. I realize I average 10.3 miles in City and 12 for Highway.

Am I missing something? The new MPG sticker says 16 City and 22 Highway and 18 in between.

Is it because something wrong with the engine or the gas I use? I really do not need to average what Hummer's do in MPG.

Please help!

 

I guess my first question is how are you calculating your gas mileage. How do you really know you are only averaging 12 MPG on the highway? The only accurate way to figure your gas mileage is to take an odo reading with a full tank of gas, then take a reading when your tank is empty, figure the miles you drove and divide it by the amount of gas needed to fill your tank. If you are using your computer and looking at the instant MPG, that can be all over the place.

I have averaged anywhere from 13 MPG (mostly city, with a heavy foot) to 23 MPG (all highway avg 75 -80 MPH) in my XJR that has had many performance mods to it.

 

i get anything from 16 mpg around town, to 26 on a run steady 80 odd mph

 

I run 17-22. But of course, I'm getting that from the onboard computer, so I don't put a lot of faith in that. Like mentioned above, the only TRUE method of figuring it out is to use the odo and average a few tanks.

 

I get between 17 and 20 in the city and 24 to 26 on the open highway. (manual calculation) I have a 30 mile commute to work which is about 2/3 highway speed. On board computer prefers 19.5

 

You may have a tiny air leak going into your engine .. That mileage is pretty bad if it's accurate .. If it is I wud get your fuel trim read.

 

Good Morning jag_genius, (well, morning here)

Are you saying that my 17-22 is bad on my XJR? Should I be looking into it? When you keep your foot out of it, do the XJR's get worse milage, or better?

Thanks! I guess it's time to do a true milage check...

 

hey
no i mean jagsters mileage is bad.. yours is accurate.. i get the same.. well i get city 18.0 and highway i get 23-24 .. but i have a new engine.. but now it shud go down... got a 2.5-3.0 psi supercharger pulley going in this week... and a bigger supercharger cooler coming.. so i guess it will drop a bit.. we'll see.

 

Yes, I read the on board computer Average: is 10 sometimes I get 12 if I drive far. I am sure I'm not reading the Instant average as it fluctuates a lot.

Where and how can I get my fuel trim read?

I am looking into getting a LR Disco 4.6 and by the MPG stickers it gets better mileage than my XJ 4.0 right now.

Thanks any help is appreciated!