Okay, trepidation to find a simple answer to my question but got bogged down in tech talk and stories of ...well, what ever...lol.
Okay. I'm taking a 1k mile trip in my 2003 XJ8. I will be averaging 80 mph on the hey. Should I engage the sport mode or not? And what are the advantages/ disadvantages of sport mode on or off on the hwy?
Many thanks!

 

I've got some SERIOUS auto correct going on here...tried to find (not trepidation) and hwy (not hey)

 

Depends on how you like to drive? Use both to see, the Sport will give you a bit longer aggressive shift, thus eating a little bit more fuel getting up to speed. But it won't effect cruising speed, mileage will be the same.

 

Now THATS what I was looking for! Thank you!

 

Hoping you've read through this too:
https://www.jaguarforums.com/forum/x...t-mode-185643/

Probably goes into a bit more detail and discussion than was really needed, but the same basic answer was there