BenzManNy

Is anyone running regular gas on the W204? I had a loaner from the dealer a few weeks ago and was running regular gas for like 6 days and noticed no difference whatsoever.

BenzManNy
Manny

snowmuch

...

ilumunus

You are REALLY not supposed to do that....

BenzManNy

I was just wondering. My car always run on premium.

Glyn M Ruck

These cars have a very broad MAP switched on that can be changed with a Star. They will run on regular but with timing substantially retarded. This has an adverse effect on efficiency & fuel consumption. You really should use premium.

C300CA

Before I left dealer with my brand new C, salesman filled in with regular gas. I wasn't very happy with the way they just saved a few bucks. However, I didn't feel anything abnormal. After the 1st tank, I always fill with premium gas as user's manual suggests.

C230Kompressed

93 octane or better. Us Californians have to deal with ****ty 91 **** octane, but we have no choice.

vipsa

The ECU fuel map is optimized to run on 91 not 93, so there's absolutely no difference between running 93 and 91. The only way to fully utilize the 93 OCT is to get an aftermarket flash for that octane rating. If you look at your gas cap, you'll notice that it recommends using 95 RON which converts to 91 AKI/PON (US Octane Rating)

Drazil

Over here only one gas station, Sunoco (I guess Petro Canada now) offered 93 octane and charged an extra 2-3¢ on top of premium for it. I never put it in, but psychologically when you're given the option of what is perceived to be a better product, you'll usually go for it if you can afford to. That's why I always avoided Sunoco.. I always felt like I was cheaping out by not using the standalone 93 octane pump

I only go to Shell because they're the only ones who don't add ethanol to their 91 octane. I'd rather be ethanol-free than 93.

speedgoat

Always use regular in mine. Can't tell any difference in performance or fuel economy.

Glyn M Ruck

There are certain urban myths being expressed on this thread.

The standard US MAP for the M272 ECU is not optimised for 91 AKI. It is actually a broad & tolerant MAP. There is a standard MAP in the ECU that is optimised for 91 AKI or greater that can be switched on with a Star. This can only be done if you never go near regular because it does not allow the system to retard timing sufficiently when the knock sensor detects the onset of knock & runs the timing more advanced. Thus you could do engine damage if you put regular in the car. Benz consider it too much of a risk so they select the broad MAP as standard and it is just as well they do with the number of people that mess with regular.

Running regular will affect potential performance & have negative consequences for fuel consumption. This is very easily demonstrated on a decent dyno with a high compression quad cam engine like the M272.

zero0809

I was told by the dealer that I should only go to Shell, Sunoco, and BP gas stations, he say only these gas station are clean with their gas

Glyn M Ruck

More nonsense from dealers.

vipsa

I'd much rather fill up at a no name gas station that's newer than an old raggedy Shell. Reasoning being that the newer gas station's tank (not always) will be newer and there's less chance of them being rusted out and have contamination in the gasoline.
Also NEVER pump gas while the big gas truck is refueling the Gas station's tanks. That's usually where all the crap from the bottom of the tanks gets kicked up and can go in your gas tank. While most of this will get filtered out I'd rather not deal with it.

Sportstick

Glynn,

Wouldn't you suggest staying with TopTier products for the sake of the detergent package, and being able to avoid having to do Techron separately?

http://www.toptiergas.com/

gyess

So the timing adjusts automatically based on grade of fuel. What is the major concern?

vipsa

Read up: http://en.wikipedia.org/wiki/Engine_knocking

gyess

Thanks Vipsa. I am familiar with knock. With the sensing and variable timing, I would think it is not a concern. I have run 89 one in awhile in mine and it is fine.

robnyc

^^^ I recommend this as well. Been using TopTier products the last 3yrs on my Cadillac 2006 that had 127,000 miles (Shell 90% of time, Exxon/Mobil backup), BMW 07 (Shell 90% of time, Exxon/Mobil backup) and now my MB been using Shell premium and will consider BP as a backup now that made it to the TopTier list over Exxon/Mobil.

Get the Shell Savers Card and save on each gallon or their Fuel Rewards Network card to save even more. I had Exxon/Mobil speedpass but it's only convenient if u dont have cash and are in an emergency to fuel up.

stratman1954

As a former gas station owner I can attest to this.

stratman1954

I use the mid grade and it seems o.k.

davesc300

My BMW 740i runs well on any octane above 89, with no cautions from BMW. However, based on the on-board mpg computer, 91 octane yields at least 10% better mileage at less than 5% cost difference.

Due to MB's warnings, I have only used 91-93 octane in my C300. A recent 500 mile stint from MD to MA running 80mph+, the onboard trip computer indicated 28mpg--this from the C class (2012 C300 4matic) which reportedly has the worst mpg rating.

gyess

Dave, imhave rhe same car and i am impressed with the mileage i get on a highway run. Overall i drive it pretty hard and i can get anywhere from 24-28 depending on traffic flow.

Eltee

OK, let's do the math here. If you drive the typical 1000 miles per month and your getting 25mpg that means your buying 40 gallons of gas.

If you're really cheap (which is what this is all about) then you can find premium for $0.20 more than regular. So that will run you a whopping 8 bucks a month extra to keep your $40,000 luxury car running it's best and probably run longer. Around here we have midgrade at 89 octane and premium at 93 octane so you can mix your own and save even more.

The argument about I can't tell the difference is like using K-Mart brand dino oil and saying I can't tell any difference. Of course you can't tell the difference but just wait a few years and see what happens.

So knock off being so cheap and treat your car the way you should. I'm sure most of us are reallly **** about how your car looks and how clean you keep it so do the correct thing for the engine too.

(Sorry, lost it there.)

Samaral

+1.