MP4.2+6.0

FWIW, up to you. As I mentioned, no ill effects when I use mid grade on NA W12 or Q5 2.0T. Again, knock sensors make these a lot different than old school motors. For me the 67 Chrysler 383. Yep, needed premium when newer at 10 to 1; didn't by late on as motor tired out. Also had a distributor cap, rotor, coil, wires, vacuum advance, mechanical tranny kick down arm and needed plugs every 5 K, and pre- even copper for that matter back then. Or, the cast iron block and heads, guess work on cooling jackets, etc. Different world with modern motors, castings and metallurgy, electronics mapped against numerous inputs, knock sensors, etc.

Motors (ECU) also don't learn anything particularly relevant in x miles. Throttle adaptation may come into play, and tranny adaptation, but both functions of how much you put your foot in it, or not. ECU learning would be in mixture if MAFs are tweaked, O2's aging and so on. Basic timing logic is move up until it pings at a tiny level, then back it off. Goes on constantly, including during engine temp changes over any driving cycle. Multi knock sensor set up and current electronics also provide triangulation and then can time on a cylinder specific basis.

What they can do over time is get gummed up, but that is now more a non Tier 1 gas issue and oddly possibly a lesser issue with FSI. That is, a port motor benefits from washing the intake valves w/ fuel. Definitely could happen and affect running over the miles on a port motor when folks when from a Chevron or Shell or other Tier 1s with additive packs to discount du jour unmarked fuel trucks, no additive pack, whatever the octane. On FSI, all you get (unfortunately) no matter what additive pack is injectors cleaned and maybe piston crown a bit. Of course correspondingly, an FSI is more prone to intake fouling (typically from oil vapor/PCV system and cold condensation crud) without fuel to wash it off, whatever the octane and whatever the additives. I would still use a Tier 1 gas, no matter what octane I was using, even if on FSI it is really just about the fuel system and not the intake particularly.

Other than that, I don't expect the world to end, particularly not against a motor, cooling and tuning set up designed to run on the Autobahnen at 90F + summers for many hours at 100-155MPH, and full torque acceleration that may last much of a minute, not seconds. Just not the U.S. environment no matter what geography. 100-155 is a whole different world, and that is what all the systems are built for--or arguably somewhat more since the USA ones tend to get a fair amount of the "warm weather" cooling parts. Chip guys presumably don't think so either, since they are basically upping the boost and maybe playing w/ the timing a bit but not suggesting you need to go to racing fuel. Implicitly, what I think they are doing is more about knocking out the built in margin from regular to premium.

Jack88

As always, the informative response is appreciated MP4. I'll be going back to premium, this was just an experiment. Incidentally, my check engine light came on, and I left my cable in Michigan for Mitch to use. Ah, well, it goes in for it's 65,000 mile service on Thursday (it's at 70,000, previous owner ran late a couple times.) and I'll just see if they scan it as a courtesy with the service.