The very first MB I owned I put in cheap gas and the car was pinging. My mechanic told me to never use anything below what is stated by the manufacturer. No damage was done but it was only a half a tank. Ever since then I put the Premium stuff in my car. The highest price I paid for gas was $5.08 a gallon!! It has actually gone down to $4.69 a gallon so I don't see it going up at this time. I knew exactly what I was in for when buying each of the MB's I have owned. I know they are high maintenance, expensive to maintain if you are not a DIY but nevertheless it my choice to drive it. I treat my car like a child. It is always serviced when needed, well maintained and it cost money! For anyone who wants to drive a MB I say do your homework and know what you are getting yourself into. A friend drives a Honda Accord and wanted a used MB like mine and when I recommended the extended warranty she asked why? I told her why and when she found out that it is far different then her Honda to maintain she changed her mind, She is way too cheap to buy an extended warranty so not a fit for driving a German car. I will have to replace my O2 sensors soon and have new brakes and I am prepared to spend what I need to on it. It always behooves me that someone will buy a MB and expect to maintain it like a Toyota or Honda
I say use what you want to use. Keep an independent mechanic in business. There is so much crap written on the subject that I could care less.
You want to save more money? Cut back on the meals out to restaurants to once a month. Cut back on the video games that yo buy to one a year. Cut back to going to the clubs to never. Cut back your cell phone plan to a call only instead of a text everything internet everything special.
Now you are saving some dough.
Come on people, I mean really, what is the monthly difference in Regular and Premium? Add it up! It might be what, $50? Start looking for real solutions and low hanging fruit is what I was always taught.
__________________ Who's John Galt.
"Timeo Danaos et dona ferentes" - Virgil, The Aeneid, Book 2
I was a teen and high test was 103 octane(real octane) and cost(1967) 34cents a gallon and I ran a hopped up 1957 Chevy Belair convertible with 12.5 to 1 compression,it was an easy decision to choose high test.I valued the engine I built with my own 17 year old hands.41 years later it still is an easy choice,I value the engines I work on and like to drive.
I would like to make a suggestion.
For those, that would like to use regular in their V6 engines with well over 200 HP.
The proper way to do it would be lowering the compression. You can put double head gasket or even bore the head chamber.
This way instead of 230 HP you will have 180, but you'll be able to run on regular just fine.
Or better yet, buy 180HP Toyota and don't waste our time on this forum.
I would like to make a suggestion.
For those, that would like to use regular in their V6 engines with well over 200 HP.
The proper way to do it would be lowering the compression. You can put double head gasket or even bore the head chamber.
This way instead of 230 HP you will have 180, but you'll be able to run on regular just fine.
Or better yet, buy 180HP Toyota and don't waste our time on this forum.
This question is for the Mercedes Gods, Greg210 and Ohlord! I am curious about combining octane levels, ie. does 1/2 tank of 89 and 1/2 tank of 93 equal out to the required 91 octane? I've never done it, and I am not cheap enough to even try it, but curious enough to as the gurus!
be close or fill with 93 and at half way point fill with 89 the next fill up,at least that would save time.
summertime in New England hot plus 100% humidity I would feed it the 93 and about 1/4 tank 89,maybe even 17% 89
ohlord
Vehicle: 2001 E320 - Brilliant Silver/Ash: MBCA member
Location: The Mountain State
Posts: 6,381
Assuming your tank is empty, 10 gallons of 89 + 10 of 93 = 91. The next time you fill up, you'll have to pull out the calculator or at 1/2 tank add 5 gallons of each. Is it worth it to save 50 cents? You be the judge.
Put all the questions of whether or not you will damage your engine aside for a moment, and focus on the OP's question at hand: will changing to regular from premium save me money? The answer is no. You aren't going to save an appreciable amount of money, and here is why:
As the article you cited clearly states, the lower octane will result in a loss of performance. So at any given RPM your engine is making less power than it would on the premium fuel. Since your car requires a fixed number of horsepower to achieve a certain speed you will have to use higher RPM under any circumstance in order to acheive the exact same speed as you did with the premium fuel. More RPMs means more fuel used. I've known people who have tried this on their own vehicles (and I wouldn't on mine) and have found that over the course of a few tanks of gasoline their MPG actually decreased.
So you're going to risk damage to your engine and catalytic converters and not save an appreciable amount of money. You could actually wind up spending more, depending on how aggressively your ECU dials the spark back in order to account for the lower octane.
The very first MB I owned I put in cheap gas and the car was pinging. My mechanic told me to never use anything below what is stated by the manufacturer. No damage was done but it was only a half a tank. Ever since then I put the Premium stuff in my car. The highest price I paid for gas was $5.08 a gallon!! 
It has actually gone down to $4.69 a gallon so I don't see it going up at this time. I knew exactly what I was in for when buying each of the MB's I have owned. I know they are high maintenance, expensive to maintain if you are not a DIY but nevertheless it my choice to drive it. I treat my car like a child. It is always serviced when needed, well maintained and it cost money! For anyone who wants to drive a MB I say do your homework and know what you are getting yourself into. A friend drives a Honda Accord and wanted a used MB like mine and when I recommended the extended warranty she asked why? I told her why and when she found out that it is far different then her Honda to maintain she changed her mind, She is way too cheap to buy an extended warranty so not a fit for driving a German car. I will have to replace my O2 sensors soon and have new brakes and I am prepared to spend what I need to on it. It always behooves me that someone will buy a MB and expect to maintain it like a Toyota or Honda 
Octane 
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