what is the best octane to use in the v8 and what kind of mileage should I expect both in town and road...thanks.

 

I have done tests on both my 99xk8 and my 95xj6 and I put the results on my page. Many will differ but with my wife’s and my driving I see no advantage to the higher octane other than having your engine run cleaner. By the way the 99xk8 is a daily driver. http://www.gusglikas.com/AutoRepairMPG.htm

 

I use 93 or higher. Jag's don't like cheap gas. I get around 17/18 on average, more if I'm on the highway a lot and less if I'm in stop and go traffic or making frequent trips.

 

UK and Europe standard is 95 octane, but 97 is available at a higher price. Yesterday I paid 116.9 pence a litre, which means it equates to £5.31 a UK gallon ($8.3). Yes, we English certainly suffer if we enjoy Jaguars !!

 

Long, involved, subjective discussion!

Bottom line: To achieve the HP advertised by the manufacturer you need to use the octane recommended in the owners handbook.

Other opinion: The car is designed to manage engine knock (ping) through knock sensors and spark advance management by the ECM. Therefore, using 89 (US) octane will not cause pre detionation. The car will no longer be able to achieve the advertised HP but, personally, I would never be able to determine that.

Great l o n g discussion here:

https://www.jaguarforums.com/forum/s...ad.php?t=31594