About the premiun vs. regular. Recently I drove my '04 E500 from Burlington, ON to NYC (500 mi/800 Km) on two occasions. Driving conditions identical, the first time I used premium gas and got 27.3mpg/8.6l/100Km, the second time I used regular and got 28.6mpg/8.2l/100Km. That is almost 5% better gas mileage with the regular gas and I thinkI had the A/C on most of the time the second time. I did not notice any change in response or acceleration.
Even 8.6l/100km is very good mileage, never mind 8.2l/100km. Just curious, are your plugs' and gap OEM? If not, what are you using? In addition, did you do any modifications to the ignition system in any way?
Usually, after people have put in premium gas, they either get no improvement, or some improvement, but not poorer result. This is because if the engine has a knock sensor, the ignition timing can be advanced. If the engine is not equipped with a knock sensor and the engine isn't pinging, then it is unlikely the car will see any improvements.
Having said that, if the ignition system is non-standard and can produce a spark that the engine can take advantage of the more-readily combustible quality of lower octane gas, that it can offset the advantage of a slight increase in ignition advance that the premium gas would invoke. However, better fuel economy usually comes with better throttle response and/or snappier acceleration. Typically, the driver needs to press the gas pedal less for the same acceleration, or to maintain a particular cruising speed.
Interesting discussion....here's something to check out. What's the max permissible octane a Benz can handle? I've a 2005 C-230 kompressor, and have gotten as high as 36 mpg(down Cajon pass I-15 California) and averaging 30mpg overall (up and down the pass). Had an idea to fill up with some 100+ octane with the idea of improving mileage, but don't want to do this 'till I get some feedback from some of you.
Even 8.6l/100km is very good mileage, never mind 8.2l/100km. Just curious, are your plugs' and gap OEM? If not, what are you using? In addition, did you do any modifications to the ignition system in any way?
Usually, after people have put in premium gas, they either get no improvement, or some improvement, but not poorer result. This is because if the engine has a knock sensor, the ignition timing can be advanced. If the engine is not equipped with a knock sensor and the engine isn't pinging, then it is unlikely the car will see any improvements.
Having said that, if the ignition system is non-standard and can produce a spark that the engine can take advantage of the more-readily combustible quality of lower octane gas, that it can offset the advantage of a slight increase in ignition advance that the premium gas would invoke. However, better fuel economy usually comes with better throttle response and/or snappier acceleration. Typically, the driver needs to press the gas pedal less for the same acceleration, or to maintain a particular cruising speed.
Interesting results indeed.
I've heard that lower octane= better mileage, but i find driving style/speed has a bigger impact. For example, I got 7.6l/100km on my 04 e320 4matic today over 220 km. I was averaging 85km per hour (needed to arrive somewhere at a certain time and was early, so drove slow-never thought i'd break 30mpg with this ancient engine). When averaging 110km/h, i get 8.5-9.0l/100km highway. When averaging 120km/h, more like 9.5-10l/100km.
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