I have been using Tesco diesel @ 93.9p per litre and get about 430 miles to a full tank (48 litres). That works out to be about 41mpg or 10.41 pence per mile.
I went to a BP garage recently and used the BP Ultimate diesel, this was 96.9p per litre but I got 500 miles out of a tank (again 48 litres). This works out as 47mpg or 9.90p per mile.
I know its only a fraction of a pence but I reckon BP is better for your car than the Tesco sh*te. I need to get a life too
p.s mine is a 130bhp