Fuel grade / emission warning light

[aga]

i have a 04 1.4s polo ( 75 bhp ) with a intermittent emission warning light. The VW dealership suggested using unleaded 97 instead of UL95 as a means of stopping the light plus they say it will give better performance.
Has this been suggested to anyone else and does it have any merit.

[perse]

I have a friend who has a Lupo Gti, he was told to use 'super unleaded' in his to cure this fault!.
My wife has a 2000 2.0 beetle, the emission light keeps coming on in that. It has been in the local VW centre 4 times now!:aargh4:

[aga]

the dealer eventually changed a H02 sensor and since then no warning light, so i think that the fuel grade suggestion was a red herring and a means of not doing the work ( or is that too cynical ) even though it was under warranty.