ok so did a little test today. Car is stock. I usually drive in individual mode with sport in pretty much everything (because i feel like it), and start-stop disabled, running 98 ron. My daily commute to/from work is about 70 miles, half of which is in motorways and half in city traffic. What i get 7in terms of consumption is around 25mpg. Today i enabled start/stop and once i entered the city, i turned drivetrain to Eco, leaving everything else intact. Behold - consumption at 31mpg, that's saving 2.7 pounds per day. Granted, temp was lower and no a/c was needed but still an improvement.
Others who've tested different modes against fuel consumption?
PS premium 98 ron sells for 1.50 pounds per liter in Cyprus these days, lower than in the UK for sure, but that's still more expensive than what we are used