Yeah, your Jag may well call for premium. Much of what I own insists on premium, so that's what they get. Though the more modern stuff would likely run fun on lower octane, 'cause they've all got modern stuff like ECUs and knock sensors. So, they should sort things out though they may be a little down on power. Amusingly, people don't understand octane very well. They think higher octane makes your car faster and other silly things. No, but if your car is designed to use 98 octane and you put 92 octane in it - you will be down on power. The reverse is not true, 'cause their car wasn't designed to run the higher octane. Of course, you can flash your ECU and change the map your fuel system uses and optimize for a higher octane - in some cases. But, that's an expensive and risky step to take and you're just going to end up wearing out your engine, constantly fussing with fuel delivery, and perhaps eventually blow your engine entirely. So, it's really kinda stupid to exceed OEM specs. OEM specs are specs for a reason. They're what the engineers (who know far more than Billy Bob the shade-tree mechanic) designed the car to run with.