GLOCKer

The Window tag on my 2014 lists the fuel octane next to it as 93. Is that just a recommendation or a requirement for the motor?

Troponin

The car will retard timing if you put anything less than 91/93 in it. There is about a 10+ hp difference between 87 and 93, I believe. It's safe to put 87 in it though. In fact, I am pretty sure you will take delivery of the car with 87 in it because the dealership won't waste their money putting premium in it.

GLOCKer

Good to know. I drove the car 9 and a half hours home on whatever fuel they filled it up with this past Saturday and didn't have any issues. I'd bet you're right, they probably cheaped on the fuel when they handed the car off to me and used a lower octane. My wife looked like she was about to flip last night when she asked me what I was writing about on the computer and I told her I was asking a fuel octane question for my new car. She blurted out, "You mean we have to pay $4.00 a gallon to put gas in that thing too?!"

Andy13186

This it true for Mercedes' also. I was helping my mom pick out a car (ml350) and the guy said they just put 87 in it despite it saying requires premium, and i saw him fill it up with 87 octane with their company credit card. Anyway my mom went with an acura MDX.

Im tuned for 93 so I always use 93 and I think its worth it.

Troponin

Yes, specific tuning will change that. If you get a performance tune that requires 93, the computer will no longer retard timing to prevent damage to the engine like it will stock