How much is this Shell fuel?
The Shell V-Power is a little more expensive (about 4p per litre) than standard (95RON) unleaded, but MUCH cheaper than BP Ultimate (97RON), which is usually anywhere between 10 and 12p per litre more expensive. Tesco 99 is usually the same as V-Power, or maybe 1or2p cheaper. 
Oh, with Shell V-Power, you also get "V-Power" points, though WTF they can be used for . . .
And what are the main advantages of the expense stuff apart from more getting more out of the tank?
The 2.0T FSI is mapped to run on 98RON, as the optimum standard (for performance and fuel economy). If you use less than 98RON (such as 97RON or 95RON), knock sensors monitor the engine, and will retard the ignition timing, thus reducing power, and drinking more juice in the process!
There isnt many Shell garages around here only Tesco, Texaco and Sainsburys? 
Well, if your local Tesco has 99RON, use that, and get Tesco Clubcard points too. 
Thanks for your reply. Tesco do Super Unleaded? Is that 99ron? What does RON stand for ? 
OK, RON stands for "Research Octane Number", and is a measurement of the ability to prevent knocking/detonation/pre-ignition. The higher the number, the better (for detonation resistance). It can be applied to both leaded (now obsolete), lead-replacement (LRP) and unleaded petrols. Look it up in Wikipedia for further reading.
Standard unleaded has a 95 RON. Regarding super unleaded, in mainland Europe, Super Unleaded must be a minimum of 98 RON. However, in the UK, as usual, we get short-changed - and super unleaded can be either 97 RON, 98 RON or 99 RON.
Regarding Tescos, they obviously do the UK standard 95 Unleaded. However, for their super unleaded, there are two different ones available. At some of the Tesco sites, you may still get the 97 RON super unleaded, whereas others have been upgraded to 99 RON. Tesco will eventually roll-out nationwide availablity of 99 RON at all sites.
