I use the normal shell diesel. I've used texaco, bp and esso and found shell to be better.
Most of the shell stations I go don't have the v-power one so never tried it out..
I use Shell V-Power exclusively now after I tried that and BP Ultimate diesel for severla tankfuls.
While there were no improvements in fuel consumption (63+mpg) with either, the Shell made the car run noticeably smoother, quieter and quicker. I detected no difference with BP.
ihave used afull tank once on holiday and it is definitely better for my a4 at least when compared to supermarket fuel. we were fully loaded with 4 bikes and kitchen sink I was getting 38.5 mpg then later at same speed on same road in same condition I got 41.5 mpg plus smoother responses mentioned earlier. if you can get it cheapish I would use it but its not worth 3 p per litre difference IMHO