I bought my 2000 3.0 about 6 mos ago and was getting or showing an average of 19.5 mpg Mostly city and a wee bit of freeway. I recently went on a 600 trip. MPG showed 24.5. Upon being home for the past two weeks, mpg is showing about 22 with my normal in town driving. So my question is if it resets it self upon fill up or should it be reset manually? I am also wondering if the mpg is intuitive by the car upon seeing driving habits.

 

The display is pretty good in showing you your actual fuel consumption, i.e. it is pretty much correct.
Obviously you get more miles per gallon in the highway compared to trips to town, where you have to stop all the time,'
No, the trip-computer does not reset itself upon fill up (which your consumption figures above prove) .
I have newer S-Types, hence I had to google, where your switches are: For the 2000 model, your switches should be in the hazard warning light switch:
You can toggle there between trip-switch A and trip-switch B (I always use only one, which I reset after each fill up. But if you want to know the statistics of a very ling trip, etc., you could reset the second trip switch at the start of THAT journey.
You reset trip A or trip by choosing either trip A or trip B and then press very long the RESET button (I do not know, what CLEAR does - I knew once, but forgot).
And if you find mpg boring, you can also switch over to have your fuel-consumption displayed as L/100km by pressing the mls/km switch...
And if the 2000 is like the 2004 S-Type, the toggle-switch for the various displays in the "cinema for mice" (The German ADAC-magazine dubbed it with that name when that feature was new back then in the VW Golf) is the button at the end of the left stalk switch (that is the lever switch on the left of the steering wheel). You should be able (again, if 2000 is as 2004) to toggle to the display instant fuel consumption, which will give you a much better idea, how much fuel you need at which kind of driving.

 

Went on a ling trip a while ago. Drove out to the coast to get some tasty fried cod with all the fixings. Absolutely delicious, and fresh as could be. Best ling I’ve had in a long time. Well worth the trip.

Recently heard of another new fish shop in a different town. Thought we might try it for the halibut.

 

Thank you for the response
I understand how to reset it. Just my past Japaneses cars reset on fillup. So let me ask another way. I am now back in town as I said. Even if it's not reset are the readings accurate "blended out" so to speak,

 

Karl: Yes, ling was a typo - the O is next to the I... lang , leng, ling, long, lung... (The first word in the row is incidentally German for "long"...)

Wild cat: Not sure, what your question is, but again: No, Jaguar Trip-computers do not reset at fill up. Nothing changes, when you fill up, except that you have more petrol in the tank - oh and yes: I think the computer notices that there is more fuel in the tank and it adjusts the RANGE accordingly. But in regards of the average fuel consumption (mpg): The display tell you the average since you last RESET the trip computer.