R.E92 wrote.
"There was a good article on pistonheads about premium fuel with dyno comparisons on two different cars. I can't find it now but the conclusion was out of all the UK premium fuels Tesco Momentum (99) was the best."
Taking your advice a filled up the car with Tesco Momentum (99) and have just completed a 300 round mile trip to Liverpool and back.
Trip shows Av speed as 60 mph, not bad considering the Average speed cameras and 50 & 40 mph restrictions on the M6.
Car used as near as dammit 8 gallons, 299 miles covered. That's 37 mpg, well pleased with that.
HOWEVER. When I got some items out of the boot, I noticed the exhaust tips were really sooty, is this the norm or should I be getting this looked at?