Right not my Saab has a very slight judder at idle, was all for changing the plugs as it's a common issue on this engine with the plugs running too hot but, this got me thinking a mate of mine has a Vectra VXR (same engine) he said he's never had an issue but he always puts super unleaded in it.

Do you reckon I should give (or rather the mrs she drives so she fuels luckily  ;D) should give super unleaded a try as it currently runs on unleaded from sainsburys.