I was wondering if you all have noticed a difference in gas consumption between Regular (87) Mid-grade (89) and Premium (92) fuels.... this is a purely "eyeball/guesstimate" reading, but the XK is currently being used as my primary work vehicle, no other trips or errands, and if I use regular, a full tank will last exactly one week. However, if I fill up with premium, I am able to get almost exactly two weeks use! Yeah I'm paying more for premium, but I feel that I'm getting alot more benefit from it vs. regular... What's you guy's opinion?????

BTW, I'm running the 3.7L (4X4) with K&N drop-in air filter, RC 2.5" lift and Mickey Thompson 265/70/17 Baja MTZ.....