Hi, I`ve been using diesel from tesco for the last few weeeks, taking advantage of the 5p off a litre when you spend £50 in the store. But i`ve noticed a drop in performance as well as just running a bit lumpy. Filled up at my local BP and after couple of miles the difference was noticable, more power and a lot livlier. Now i know they all fill up there tankers at the same refinary at carrington for our area and its all supposed to be the same, but i am not convinced. I have noticed this on other cars i have owned. (any similar experiences )