I though I would share my driving experience in my 2005 SLK 350. I have finished 4 trips, each greater than 1000 miles and have averaged 28 - 29 MPG with an average speed of about 70MPH. I use regular gas and have had no problems such as pre-ignition or pinging. My dealer recommeded regular gas when I purchased the car and said that regular would be fine for this engine. I have found this car to handle and drive great both on the highway and around my local area in Tennessee. I currently have a little over 8,000 miles and the tires still look new with plenty of tread and not showing any asymetric wear. I routinely check the oil level before and after each trip and so far no oil useage. I have only had a couple of minor problems so far with this car. An occasional knock from the trunk area when I am stopped at a light but id does not occur consistent enough for the dealer to locate. I also find the (audio 20) display is hard to see in bright daylight, but there is no fix for this. I even took my wife on one trip and managed to get her luggage in the trunk. So far this car is a keeper.
The engine won't be damaged if you use lower octanes. In the United States different regions have different rating for the octane anyway. (Premium is 93 in Texas but 91 in California.)
The important thing to remember is that if you aren't using 91+ in the car, not to stomp on the throttle. The ECU may not be able to compensate for pre-ig and knock when the engine is under heavy load. Under light loads though, it is capable of the needed adjustments.
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2006 SLK55 Obsidian Black w/ Black Int
Lighting, 320 Audio, 326 Premium, Airscarf, One Big Ass Smile.
Thanks for the feedback. I have a 2006 SLK350 that is at the port about to be shipped to the dealer. It is good to hear people like you giving the positive reports about their cars.
I am curious, what part of the state is Ten Mile, TN located? I have traveled most of the state and am not familiar with your town.
CMiYC - 10/8/2005 10:23 PM
The important thing to remember is that if you aren't using 91+ in the car, not to stomp on the throttle. The ECU may not be able to compensate for pre-ig and knock when the engine is under heavy load. Under light loads though, it is capable of the needed adjustments.
Thing is though, why buy a sports car and put crap fuel in it? I mean, lower octane fuel means sacrificing power, which seems ironic when you have paid a premium already to have that power available. I don't understand the need to save what is no more than small change at the pumps, compared to other running costs such as depreciation.
CMIYC - Although I am not heavy on the throttle, I have punched this car a few times to pass and just for kicks. So far no pinging or problems.
Jbanks 15 - I think you are correct on the knock, was there a fix or just live with it. It is not very loud so I am not concerned if no problem exists.
FunBenz - Ten Mile is a little south of Kingston,TN which is approximately 30 miles west of Knoxville on Hwy 40.
Steve-p - From what I know about fuel a higher octane level does not relate to more power rather it is a measure of how slow the fuel burns. The higher the octane the slower the burn. Additives are put in gasoline to raise the octane so higher compression engines, or engines with timing advanced more, will not have pre-ignition. The additives raise the price. So I think the belief that higher octane means more power is a myth.
The fuel I use in my SLK is high-octane (91) and the mere thought of putting "regular" in my tank makes me cringe. Once, with my other car, the pump attendant put low-octane petrol in my tank by mistake and I had a rough ride, poor performance and bad mileage. Besides, the seven cents more I pay per litre seem to be a pretty good investment in my case since my city/motorway fuel consumption is as low as 7,7 litre/100 km (over 36 miles per Imperial gallon or 30 miles per American gallon). Considering our climate and road conditions, this is rather good. Of course, since I am still in the running in period (±3,000km on the odometer), I drive at various speeds (an average of 100km per hour or 62mph with the occasional peak at 150km per hour or 93mph). So far, I am extremely satisfied with my car performance on the motorway. City driving is not so good but since my SLK is a leasure car, I don't care that much! [:)]
OldTymer - 10/8/2005 11:55 AM
So I think the belief that higher octane means more power is a myth.
But as you just said, lower octane fuel means that the engine adjusts the ignition timing, and this reduces the power output. In any case, in the UK we are in the unusual position of having changed from leaded fuel which was 98 RON to unleaded fuel which is 95 RON. When this happened, the average MPG on all cars (except the minority which were designed for low octane fuel only) fell by 5% on average. This is incontrovertible proof that lower octane means less power, which means you use more of it. I have done longer term tests with a couple of 911s, which can benefit from 97-100 octane fuel. In both cases, less fuel was used with higher octane fuel. My findings were that higher octane fuel was still slightly more expensive overall, but not by anything like the difference in pump price. And the engine was designed for it, and runs better on it under load.
I spent $57,000 on my SLK 350. I'm not about to worry about the additional 20 cents per gallon that premium costs over regular. I eat well and I feed my car the best fuel that I can buy regardless of the cost.
I spent $57,000 on my SLK 350. I'm not about to worry about the additional 20 cents per gallon that premium costs over regular. I eat well and I feed my car the best fuel that I can buy regardless of the cost.
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