thomas wrote:

You could try Shells super-v leaded - Its a couple of p per litre more
however its supposed to lubricate the diesel pump, improve emmissions,
performance and mpg.
No harm in filling up just the once - I use the super-v unleaded and the
improved MPG makes a no difference in cost at the end of the day (around
2mpg better but more costly per litre) however I think the cars slightly
more responsive and the other benefits also help

Most independent tests show that the extra performance effect of these
premium fuels is just a placebo effect.