M settings and resulting fuel economy

[steakandchips]

Hi,

Does anyone think that the more sporty settings on modern M cars are actually less economical on a long motorway journey? Common sense would tell me that cruising at a steady 80mph in seventh gear will require exactly the same amount of fuel no matter which mappings the throttle, suspension and gearbox are set to. I imagine city driving would probably be less economical in M1 and M2 but I wonder how much difference setting your car to Sport rather then Efficient really makes. Anybody found any great difference in the real world?

S&C

[steakandchips]

I wonder if any of this talk about turbos spooling is related to an issue I've been having recently. When I'm moving at relatively low speeds, say between 20mph and 50mph, if I press the throttle I occasionally seem to get a momentary loss of power, with an almost imperceptible lurch as the car loses momentum, before everything pulls itself together and I start to accelerate again. It doesn't last for more than a second or two but it's a definite loss of power.

It's not at all like the usual turbo lag that I've noticed since I've had the car (2013 F10 M5) which has always been consistent and isn't too noticeable. This is something inconsistent and certainly noticeable. Perhaps some gremlin in the engine management? It's not been bad enough or happening often enough to take to the dealer but I'll mention it when the car goes in for an oil service in July (incidentally, the car still hasn't asked for a single drop of oil in almost 15,000 miles).

Does this sound familiar to anyone?

S&C