[Donkey Grundle]

200,000 miles at 12k per year is around 16 years off the top of my head, I don't think that is unreasonable to spend an extra 1,333 dollars in todays dollars over 16 years for the extra enjoyment and satisfaction and cleaner running engine of the higher octane and possibly even better gas mileage. And most everywhere I've been in my life it's an extra 10 cents for every 2 octane.

Over here on the east coast we have 81-89-93 to choose from and, while it used to be 20 cents/gallon more for premium, it is now 45-50 cents/gallon difference (87-93). I drive ~25k miles/year and the gas savings was a huge reason for me getting the Mz6. Putting 93 octane in my BMW was growing more costly every year. Just dropping to 87 octane saves me ~$40/month (ignoring increased mpg with the Mz6).

Because of the now significant price difference between 87 and 93, I would only be interested in a tune for 93 octane if there was a reflected increase in mpg's.

 

[Donkey Grundle]

I don't know about you guys but lately I have seen an even further drop in MPG. I'm seeing 24.8 average now. My driving has not changed and I'm about 80% city 20% hwy...I have no idea wtf is causing my drop in MPG. I've driven my '14 for about 22k now and I've never seen it average more than 28mpg...and now it's 24.8.

Have you checked the air filter? I'm only at 13k and noticed that the engine back, especially near the intake, was already filthy.