Received my invitation to order a Model 3 today

Not that I noticed (the manual is missing). I just looked up fuel reqs online: What kind of gasoline should I utilize in my Mercedes-Benz?

 

If it's a loaner and you weren't told specifically by the owner why wouldn't you just put the cheapest stuff in?

 

If I am renting from either an individual or company, I will be taking proper car of it.
If proper care is 91 Octane, so be it.

 

Yes, while I didn't ask for a luxury class loaner, I should at least treat it with the care I'm expecting them to provide for my 3. I keep vainly waiting in expectation they'll call to tell me they have an S available, so I can finally see what all the EV fuss is about.

 

You guys are better people than I am if you are looking up exact care and needs of a vehicle you are just borrowing for a few days.

 

For me it's closing in on 3 weeks.

 

There should be a label on the inside of the fuel filler flap, or printed on the gas cap itself.
This manual for the 2017 C-coupe says 91 required; https://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/ownersmanual/MY17_C-Class_Coupe_Operator_Manual.pdf
but...
It goes on to say you can use 88 AKI, if premium isn't available. Just fill half way so you can add premium later, and not to push the car to its limit are listed as warnings. Lower octane means lower power and likely fuel efficiency.

With knock sensors and electronic engine controls, very few cars are truly premium required in the sense that putting in lower octane will result in knocking happening to the extent of possible engine damage. They tend to be supercars in which US premium is the lowest octane you can put in their fuel tank.

Also note, 91 AKI is premium inside California. In other states it could be as high as 93 AKI.

 

Yup, seems like the savings from using lower octane would potentially be canceled out by the lower fuel efficiency. I just confirmed the inside of the cap reads "Minimum octane rating 91," so I'm going to continue to play it safe. I'm saving the receipts...

 

It's likely the other way with savings. The 1.4 turbo in the Sonic was designed for Europe and higher octane, and it does get better fuel economy on it, but costs more per mile with the price difference now. Needs to be 20 to 25 cents to break even.

 

Only way to make it economically worthwhile is to switch exclusively to mid-octane for however much longer I'm stuck with it. Maybe I will. On the last fillup, premium was likely in that range at the station I found (it was as much as 30 cents lower than competitors, partly because I paid in cash).

 

The difference was in that range for a period of time during the past two springs, which is why I decided to experiment in the Sonic. Once upon time it was that way all the time. Now it is mostly about twice that. Yesterday, I passed a station where premium was 80 cents more than regular.

A 2 to 10 mix of premium to regular will give you midgrade octane, if you really want to stretch the fuel budget.