I just picked up my daughter a 2004 XJ8 Vander Plas. It's beautiful. I'm just a bit confused by a few things.

In reference to the cruise control, is there a separate button to turn on the cruise control system somewhere? The cancel/set/resume buttons on the steering wheel don't work, but, I kind of expect an 'on' switch somewhere.

The manual discusses 95 octane which I don't think we have in the U.S. Is typical premium fuel required? I'm kind of a cheapy and use the 87 octane in my daily drivers. thanks.

 

Hello mastergrumpy!

As far as I know, there is no separate "ON" switch anywhere to activate cruise control. If it does not work I believe there must be something wrong going on there. I believe you are not (yet! ) in possesion of diag-tool capable of reading Jag specific codes but that might give you some insight of what is going on with cruise control. I am using iCarsoft reader, but there are plenty more recommended on this forum that people are using with success.

Adressing second issue, I believe in US 91 would be the equivalent of RON 95 octane rating.

Take care!
Bart

 

The Jag V8 does require premium fuel. As stated above, the cruise should work just by hitting the Set button.

 

89 is no problem

 

Clock spring, could be your cruse control issue.
A Jaguar specific code reader is a good investment

 

Not saying other methods don't work, but I just hit Set+, even in town. I can't remember if Set- works for me but I suspect not for engaging cruise.
(the Owners Handbook only says that Set(+) engages cruise.
Of course you have to be doing over 17.5mph. Picture this old man wearing a HAT and enjoying his cruise control...and completely deaf to Barps I might add...
Cruise set or changes should be indicated in the Message Centre, one message being "Cruise Not Available" according to the Owners Handbook.

I should add, although the handbook says press the SET button, my button only clicks on Set(+) or Set(-). Pressing the SET logo in the middle won't do a lot for you.

 

I love driving at 17.5
Everyone stops and stares😉

 

Quick note:
If your car shows "Cruise Unavailable", check that the cruise radar face behind the lower grill is shiny clean (assuming you have adaptive cruise - a great feature)

 

Nothing to do with the OP's topic, but: I hate adaptive cruise!!! I don't want to slow down as I approach someone ahead that's going slower than I want to go, I want to pass them! Sure, the adaptive cruise will resume your speed if you move over to a clear lane, or if traffic is heavy enough I can't do that, then I just cancel the cruise altogether.

Cruise control wars on the highway are bad enough as it is. You know, where someone blocking the left lane is going 0.17 mph faster then the car in the right lane? They WILL NOT accelerate, probably because they don't even know that they can; they're "locked" on their cruise control speed! Add adaptive cruise to this, where EVERYONE will match that speed, I would be firing grenades at people!!!

 

Correct octane gas for USA is 91. So fill halfway with 89 and then the other half with 93.
John

 

From the handbook: "The preferred fuel should have an octane rating of at least 95 RON (Research Octane Number). <snip>. Some countries have only 91 RON fuel available. The vehicles in these countries are specially calibrated to use this fuel."
USA: 95 RON is equivalent to 91 AKI in the USA. It's not just spelling they insist on doing differently...

Does it matter? You wouldn't know until you've done 10's of thousands of miles and your motor carks it. (might be an NZ expression)
There was even a court case here in the last year where some poor woman (why is it always a woman?) used the wrong octane and blamed the dealer who sold it to her. Although it wasn't a Jag, one of those delicate German thingy's...

For myself, I just use the recommended octane, which is 95 RON (91 AKI in the US) or better. If you do anything else, you won't have a leg to stand on if it comes to a court case.

It's not exactly a Rolls Royce or Bentley ("if you have to ask then you can't afford it"), but what's 10c/L?

 

My US fuel door states 91 minimum, which is how it's measured in the US. We use an average of the Research Octane Number as used in Europe, Japan, and Australia, and the Motor Octane Number, which is generally 8 to 10 points lower. It's expressed as (RON+MON)/2.

91 octane in the US is the same grade as 95 octane in Europe.

You'll also find lower octane numbers at altitude. Colorado Springs, for example, usually shows about 2 points lower at the pump, with regular being 85 instead of 87. The thinner air reduces the need for knock prevention, so lower-octane fuel suffices.