I run mine on Shell standard unleaded, I've tried running it to almost empty and then running it on Nitro +, personally I couldn't tell any difference and it was no better on fuel, but that was on a 4.2, maybe the V6's make better use of it. One more small point, Jaguar engines of our era weren't really a performance engine. They're quite powerful but that's because they're big. For instance the V6 is about 80 hp/ litre whereas a type R Honda from 10 years ago was 100 and revved to 8000 rpm