I might tell you that this is unusual. In most combined cycle testing the 350 comes out the more economical for the very reason you mention. The C300 has to work harder. The 300 is the smoother of the two engines however.

 

I used to be a BMW, MB, Porsche engine management computer programmer. When you work with the actual factory development teams, you learn that the German's are extremely conservative. More importantly is comes down to an extra margin of safety for warranty claims where the manufacturer can push those costs onto the purchaser to the benefit of the factory. Secondly, there is very slight decrease in one of the measurable tail pipe emissions components. These cars are federally smog certified with high octane fuel, and thus must specify high octane fuel for daily use.

These engines have excellent knock sensors and very lazy total spark advance timing curves programed into the computer to make sure the engine never sees detonation or pre-ignition issues.

E55 with a supercharger might need 92 octane on a 100 degree day and under full power if maximum performance is desired.

As a guy who actually wrote software for these cars, I can tell you that detonation with 87 octane is a scare tactic. BELIEVE ME when I say we had design parameters that protected the warranty claim rate by assuming customers used only 87 octane.

These cars are designed for the anticipated use of lower octane, but specify a higher octane for the reasons mentioned above.

-David

 

I think I might be able to put this thread to rest. Here are some options:

1. Ride a bike. No octane issues there!

2. Invade Iraq or another oil producing country. No gasoline cost issues anymore! Yay!

3. Do whatever the hell you want. It's your car. If you don't want to follow the directions in the owner's manual, don't. See what happens...

(You're welcome everyone.)

 

Thank you David - You confirm everything I know from an oil company perspective & we have done a lot of work with all the brands you mention as a supermajor.

As you say these engines have great knock sensors. The very reason that Benz is able to make their Diesotto work is brilliant knock sensing.

 

Think that was tried by someone and didn't have the desired effect

As to the octane rating I use premium, but inside my gasflap it says "minimum

91 RON". Which is the European rating, and is equal to the 87 rating used in the States and Canada. Curious.

 

Correct - because you have a "flex fuel" engine

 

Same experience minus the mpg. My C350 is absolutely mute until 3k rpm.

 

Good point Glyn. But flexible fuel is only for US cars, according to my handbook,
not my Canadian version. So is the label on my car a Freudian slip???? Perhaps the premium gas really is just to pass emissions testing, as per the knowledgeable post by dw8 above.

The 3.6 CTS motor is near identical to the MB 350, in spec, but only needs 87 gas. Hmmm......


Cheers

 

Thanks for your information. I love posts like this and it confirms what we all suspected. I'll quote you in the inevitable future octane wars between people who are realists (me) and those who think 87 octane killed Jesus.

 

According to the C350 handbook, if you choose to run less than 91 octane you should be blending your tank, and not filling full tanks of it. Also you should fill your tank with premium fuel as soon as possible. They further warn you not to exceed 2/3rds of your RPM range, and that unburned fuel may collect on your catalytic converter and ignite causing a car fire.

I wouldn't complain about the Canadian version vs the US version, you get all the nicer options and who wants to burn flex fuel anyways? E85 is toxic, caustic, and delivers less energy than an equal volume of gasoline. Bottom line it's a bull**** technology that's probably wasted trillions of dollars. I wouldn't be surprised if an engine that could run off it could also run off of lighter fluid and dreams.

 

And you believe this to be true? It's that American's are so addicted to litigation. They're trying to cover their a$$ to prevent being sued.

For reference, in my W203 handbook it says not to switch between "S" and "C" modes of the transmission while the car is in motion or it might cause "loss of control". This is total lawsuit-avoidance-BS.

You're being too gullible. Sorry.

 

Your car might well be a hybrid without without alcohol conversion components but the Flex mapping. That's how our SA cars are.

 

Oh I agree it's lawsuit-avoidance.. but I'd also point out that it would suck to be that 1:100,000 statistic whose car caught on fire while trying to pass someone on the highway for trying to save $2.

 

Just remember that E85 is not the only fuel in America containing alcohols. A considerable portion of the fuel pool includes 10 to 12% alcohol dosing and has for many years. As we had in South Africa for many years when Sasol had no other more lucrative outlet for their heavy alcohols.

Brazil is another example of a country with varying proportions of alcohol in fuel right up to 100% - No one gives a hoot about aldehydes in the exhaust gas there. Mercedes is a big player in Brazil.

 

I think the entire country of Brazil is 100% sugar-based ethanol, but the cars are fitted to support it. Just because they do it doesn't make it a great idea. An E85 advocacy website : http://www.change2e85.com/servlet/Page?template=Myths

"If I put E85 ethanol in my non-Flex Fuel vehicle, it will ruin it. One tank won’t hurt. Some dealers are spreading rumors and charging $300-$3000 for one tank of accidental E85 use. This use may cause misfiring and a rough ride. Your check engine light will come on. If you should accidentally or on purpose put E85 in your vehicle, drain the tank, put in regular gas and all will be well. If you use E85 without a conversion kit or non-Flex Fuel capable vehicle for an extended period, you can damage your engine."

Also this statement is very misleading:
"It is true that a vehicle does require more E85 than regular gas since the amount of energy per unit of ethanol is less than that of gas. Ethanol has a lower ignition temperature so the engine overall will run cooler increasing power. It also burns slower so instead of just burning out in one violent explosion forcing the piston down, it continues to burn the entire length of the piston stroke expanding gases more evenly and smoothly. So running E85 will give any engine more power over any pump gas. Also E85 is 105 octane. Gas comes in 85, 89 and 91 octane. The 105 octane of E85 will help to eliminate knocks and pings. All of these benefits will make an engine run smoother and quieter."

I will buy a hat and eat it if forcing an engine designed for gasoline to burn fuel slower and at greater volume to create equivalent work is an improved fuel source. My car will certainly not increase in bhp because I filled the tank with E85.

From the National Ethanol Vehicle Coalition:
http://www.e85fuel.com/e85101/faqs/conversion.php

The only kit holds EPA certification is by FlexFuel U.S. You can find more information on this kit at www.flexfuelus.com. Technically speaking, converting a vehicle that was designed to operate on unleaded gasoline only to operate on another form of fuel that does not use the FlexFuel U.S. kit is a violation of the federal law and the offender may be subject to significant penalties.

The differences in fuel injector size, air-fuel ratio, PCM calibrations, material composition of the fuel lines, pumps and tanks are just a few of the components that contribute to making an E85 conversion extremely complex.

 

They even have a list of year / model Mercedes that are E85 compatible. Also, I mean that 100% of the country uses sugar-based ethanol, not that the ethanol is E100. You can't have a tank of 100% pure alcohol as it will literally take water out of the air.

http://www.e85fuel.com/information/f...s_ffvs2009.pdf

 

Brazil is certainly not 100% ethanol or we would be out of business, as would Petrobras & Ipiranga. Brazil's sugar cane producers play the swings & roundabouts game dependent on market pricing fluctuations of sugar & alcohol - encouraged by the government.

You need a reality check. Benz now build the 204 in China and import the rest of their requirements. The Benz brand is hugely popular with the growing affluent of that society & in Asia generally. Having driven the length & breadth of that country while restoring our business there & probably spending 4 months a year for nearly ten years in that market - if you think that Benz cars in China are going to religiously run on 95 RON Eurograde you can forget it. Fuel stations sell what Sinopec, CNPC, Petro China etc give them. Benz won't stop selling cars there & the cars won't fail.

I'm not a proponent of E85

 

Indycar run on 100% ethanol. Volkswagen and other manufacturers produce 100% ethanol vehicles in Brazil & have for many years right back to the old carburettor Santana (Passat)(pure zinc bodied carb - no copper present in the alloy to prevent catalytic corrosion with water present aggravated by low temperature below the venturi). Yes you have to try and keep it as anhydrous as possible. It's not possible of course but manageable.

BTW - VW shipped that same Santana plant to China where it is today's most popular taxi.

 

Not complaing! And I agree turning food into fuel is daft.

In Brazil I believe they use a waste product that's left over from harvesting cane. As far as I know they don't actually grow the stuff to make fuel.

 

They certainly grow cane to make fuel by design. We supply at least 30% of the sugar mills in Bazil. We run Lubrication for the Sugar Industry Seminars in Sao Paulo annually - Campinas being one of their largest production areas.

Brazil could not sell all their sugar if they converted their cane harvest to sugar. The world price would collapse. They have enough trouble keeping it above 10 USc/lb as it is. It's at the best level in years at the moment.

The only waste is bagasse which is converted to methane for boilers & pulp for the paper & board industry & some other minor offtakes. Many of their mills today are fully integrated to make sugar, alcohol, consume their own byproducts to boiler & a paper mill. Thailand is following suite thanks to some of my personal efforts. Kaset Thai in Thailand being the first integrated mill there and also the largest sugar crushing train in the world.

The converse also applies of course - If Brazil converted their production to fuel the world would suffer a sugar shortage.

 

Thanks Glyn

 

A pleasure - BTW - I agree that growing & diverting food crops for fuel is crazy. In general only waste biomass should be used.

Brazil's case is different. Their intention goes back to the early seventies fuel crisis when they decided to develop an alcohol fuels program to avert a squeeze on their economy & today produce so much cane that they have to use it for fuel. Brazil controls the world's sugar business & production followed by India, China & Thailand.

This year with increased sugar prices Brazil has diverted 43% of cane for sugar production with the majority still going to ethanol. Government has now legislated a max area for cane growing to prevent deforrestation etc.

In my opinion, Brazil is likely to be the only country in the world to continue achieving a totally viable biofuels industry due to efficiency, advanced technology & the vast amount of arable land. They have to stop cutting down rain forrest however & it's good to see the government step in. Brazil is generally a very sensible & pragmatic country - all things considered.

Their flex fuel cars typically can run on E100 hydrous alcohol & E20 to E26 alcohol petrol blends that use anhydrous alcohol to prevent phase separation. A Benz there would typically run on E20 to E26.

 

the C350 is only more expensive by $2500 when you throw in the same options and dealerships gives more incentive on the C350 so they can make money on the C300 because for whatever reason people think buying the C300 is cheaper and then proceed to get P1, P2, and MMI which adds up the cost.

and my C350 was only $35540 OTD that had a msrp of $37775. someone in VA last year bought one fully loaded for only $38k OTD granted their state tax is low.

ooh...and I avg around 20mpg in my 350, so I'll agree that the C300 is more fuel efficient. however I can probably avg better mpg if I don't live in the hilly suburb.

 

just want to add C350 produces 268hp using a 3.5L. BMW's 3.0L NA engine made 255hp in the 2005-2006 330i/530i/730i. Nissan's 3.5L is making 330hp in the G37. 268hp is nothing really to be impressed about. it's barely adequate between it's main competitors.

nothing to do with being forced induction or not. ever wonder how much faster a 3.0L in a W204?? oh wait...that's a C300.

what I want is the 3.5L M272 from the SL350 in the C350.

 

a up for Glyn in this thread.

plus the fact all California gas contains up to 10% ethanol.

running 87 or 89 saves you around $200 maybe $300 at most a year. not worth the saving to have your engine making less hp due to lower octane rating. There is no damage can be done running 87/89 octane except it's not going to make the power as it should.

Honda or Toyota or Nissan only require regular just to make them seem more affordable. In reality the HP rating of their vehicle are all done with higher octane rating. Our 2005 Odyssey ran like **** (no power) when we fill up with 87 or 89. We ended up using 91 anyway.