I did some runs on tesco 99, and also V power, there is a difference, more in smoothness, tesco being better, and also a slight difference in mid range, better on tesco, but top end better on v power, I'd be happy using either, one is a 10 mile drive the other a 15 mile drive each way!!
Haven't noticed any starting or cold idling issues on either, even with running no iscv, winters day still start no probs, just hold for 10-15 secs.
tabetha