StepheninSpruce Posted June 15, 2016 Share Posted June 15, 2016 I've got a 2013 AWD Fusion with the 2.0 ecoboost. I've been monitoring fuel economy and trying different fuels. Most of my driving is my daily 100km (60 mile) commute. To ensure my sample size is not overly impacted by specific variable driving conditions, I've been monitoring data for about a year and alternating my fuel types every month. In that year, here's what I've noticed: With regular fuel, I average approximately 9.8 L/100 km (24 mpg). With premium fuel, I average approximately 10.8 L/100 km (21.8 mpg). The range for each is + or - 1/10 of a L/100 km. So with regular fuel my monthly economy has been between 9.7 to 9.9 L/100 km and 10.7 to 10.9 L/100 km. So, in summary, with my sample over the course of the past year, I use approximately one additional litre of Premium fuel for every 100 km I drive MORE than I do when I use Regular fuel. Any idea why my fuel economy is better with Regular than with Premium? Anyone else done the comparison? Thanks 0 Quote Link to comment Share on other sites More sharing options...
Monochrome11 Posted June 15, 2016 Share Posted June 15, 2016 My guess is your computer is adjusting the tuning to give you more power with the higher octane. You in response are using that extra horse power and the use of more power consumes more fuel. Another thing is higher octane fuel can contain more ethanol to boost the octane. Ethanol has higher octane but provides less gas mileage. 0 Quote Link to comment Share on other sites More sharing options...
WWWPerfA_ZN0W Posted June 15, 2016 Share Posted June 15, 2016 (edited) x2 on the fuel quality. Possibly the 87 has no ethanol, and the 93 has 10% (E10). And/or you are enjoying the better throttle response from 93 (i.e. driving more aggressively), which will of course in turn decrease fuel economy. Sometimes there are more detergents in premium fuel than regular. If those detergents are cleaning out significant amounts of deposits, it is possible for economy to drop temporarily, though usually not this much. Edited June 15, 2016 by WWWPerfA_ZN0W 0 Quote Link to comment Share on other sites More sharing options...
Rtipping Posted June 16, 2016 Share Posted June 16, 2016 Lately I have been experimenting with easing up on the gas pedal the car does not go as fast but the gas lasts longer. Seriously your milage looks right to me I have the 2016 awd titanium Im about the same . 0 Quote Link to comment Share on other sites More sharing options...
StepheninSpruce Posted June 21, 2016 Author Share Posted June 21, 2016 I'm not sure the ethanol is a factor. I'm not exclusively loyal to a single gas provider but one that I frequent only adds ethanol to the lower octanes (at least according to the sticker on the pump). The 93/94 octane is ethanol free. Also, I don't think my driving is a factor. Most of it is just highway commute in traffic with pretty consistent speeds. And since my sample is spread over a year I think it would average out. One petro chem engineer I spoke with posited that the engine may not be designed for higher compression (high octane) fuel and that as a consequence, some of the fuel may not be getting combusted and may just be discharging/leaked out. I have no idea whether the 2.0 ecoboost is a relatively high or low compression engine though. 0 Quote Link to comment Share on other sites More sharing options...
Monochrome11 Posted June 21, 2016 Share Posted June 21, 2016 It is true that engines that are tuned for regular gas may get worse gas mileage with premium gas because it tends to burn at a slower rate and may have some of the power going out the exhaust. I doubt it is not getting combusted, it just may be combusted at the wrong time to deliver the most efficiency. However, I thought the ecoboost engine was design to run on premium gas but it detunes itself when regular gas is used. Maybe that is not true. Your driving could still be a factor. MPG is mostly effected by acceleration and you still need to do this to get up to speed. I am sure you do it several times during your commute. You may not even know you are using that extra power. Then again, this is all dependent on the Ecoboost engine being able to tune itself for different octane fuels. 0 Quote Link to comment Share on other sites More sharing options...
akirby Posted June 21, 2016 Share Posted June 21, 2016 Higher octane fuel isn't harder to burn - once you put the spark to it then it's no different than regular. It just resists spontaneously combusting before the spark. The reason lower octane can result in less power and worse fuel economy in vehicles tuned for premium isn't the way the fuel burns. Lower octane causes the timing to be retarded to prevent spontaneous combustion and it's the timing that reduces power. Likewise, higher octane allows the timing to be advanced (allows the spark to occur later) yielding better power and more mpg. 0 Quote Link to comment Share on other sites More sharing options...
drolds1 Posted June 21, 2016 Share Posted June 21, 2016 One petro chem engineer I spoke with posited that the engine may not be designed for higher compression (high octane) fuel and that as a consequence, some of the fuel may not be getting combusted and may just be discharging/leaked out. I have no idea whether the 2.0 ecoboost is a relatively high or low compression engine though. No. Your engine is designed to develop peak HP on premium fuel. The CR of your engine is 9.3 to 1. You owner's manual states: Premium fuel will provide improved performance and is recommended for severe duty usage such as trailer tow. That said, if you get improved fuel mileage on regular, I'm a bit surprised, but use it. The HP difference is too little to notice. 0 Quote Link to comment Share on other sites More sharing options...
MightBeASynth Posted July 7, 2016 Share Posted July 7, 2016 Do you have Torque and an ODB scanner? The pure octane number is not the only determinant of fuel quality. The ECU tracks a value called learned octane ratio. If you have some "bad" gas (maybe water in it, too much sulfur, whatever) the ECU will see that and try to adjust. If my car is running badly or a notice bad MPG and I have not been flogging the car I will check my learned octane ratio and every time it will be 0.7 or below. Try to find gas stations that consistently give you good tanks of gas and stick to them. You may also want to narrow your search by looking at top tier fuel companies though I have had luck with non-top tier fuels as well. 1 Quote Link to comment Share on other sites More sharing options...
WWWPerfA_ZN0W Posted July 7, 2016 Share Posted July 7, 2016 The LOR (learned octane ratio) tells you what the engine is going to do with timing. If the LOR is less than 1, the engine will pull timing to compensate, and that means less power available. This protects the engine from suffering a bad/fatal event. 0 Quote Link to comment Share on other sites More sharing options...
Monochrome11 Posted July 7, 2016 Share Posted July 7, 2016 (edited) akirby, I don't know where you are getting your information but it has some misinformation. Yes, premium fuel does resist spontaneous combustion before the spark which is called pre-ignition. Premium fuel has a more stabile burn compared to regular fuel and the burn is definitely different after spark ignition. Higher compression destabilizes regular fuel and when the spark or pre-ignition starts the burn that actually increases the pressure and spontaneous combustion can take place in areas beyond the flame front resulting in more of an explosion (also know as pinging) rather than a rapid burn like you get with higher octane fuel. Yes, spontaneous combustion can take place even after spark ignition. You are actually contradicting yourself when you say lower octane results in retarded timing with lower power and higher octane allows the timing to be advanced to create more power. This is true but it is directly related to the way the fuel burns. A stabile burn is what is needed to be able to set the timing (spark) at the most efficient time. If the compression ratio is low enough, regular fuel will work just fine but higher octane will allow higher compression or more advanced timing to improve efficiency resulting in more power. I don't know how anyone can say it has nothing to do with the way the fuel burns. Edited July 7, 2016 by Monochrome11 0 Quote Link to comment Share on other sites More sharing options...
akirby Posted July 8, 2016 Share Posted July 8, 2016 I'm saying that the key is when it ignites. Higher octane prevents premature ignition and allows the spark plug to ignite the fuel/air mixture at the appropriate time. If it ignites early you have to retard the timing to compensate. I think once the air/fuel mixture is ignited it burns the same regardless of octane. I think what you're saying is that unwanted ignition can occur in areas other than the flame front while the mixture is burning and I would agree with that, but I would still call that premature combustion. The point is premium fuel doesn't burn any hotter or provide more power than regular - it just resists premature combustion better. 0 Quote Link to comment Share on other sites More sharing options...
Monochrome11 Posted July 8, 2016 Share Posted July 8, 2016 The only thing I agree with is premium fuel doesn't burn any hotter or provide more power than regular. However, its resistance to premature combustion does allow the engine to be tuned to utilize more of the power in the fuel. It is pointless to argue about your other statements because they are an opinion and have no scientific basis or logic. Then again it could just be the way you are wording it that makes it seem irrational. 0 Quote Link to comment Share on other sites More sharing options...
akirby Posted July 8, 2016 Share Posted July 8, 2016 Here is what I'm saying. Higher octane prevents premature combustion which allows a higher compression ratio and/or more advanced timing which yields more power. Once ignited both premium and regular burn the same. Premium does not burn faster, slower, hotter or colder than regular. It just resists spontaneous combustion prior to the spark plug firing. Which part is irrational and unscientific? 1 Quote Link to comment Share on other sites More sharing options...
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