got better gas mileage using premium in a regular car

[Sleeper PC 2016]

this is interesting, i filled up my 2014 honda civic (manual transmission) with premium and i got better mileage driving the same way. I went from 28ish mpg on the highway to 30 and some change. I find that interesting. But after looking at this: http://owners.honda.com/vehicles/information/2014/Civic Sedan/specs#mid^FB2E5EEW, the engine can take advantage of premium because of the high 10.6:1 compression ratio. I'm goin on a road trip to Madison, Wisconsin so we'll see if the 40 bucks i paid for premium was worth it.

[Ganz]

Most premium fuel will yield higher mpg but costs more.  But you will never save money by buying premium if you are solely looking for prices/miles.  Similarly you won't save money by buying flex fuel (E-85) because you get lower gas mileage. You buy premium (or flex fuel) for the other potential benefits. Premium being healthier in the long run for your engine and flex fuel being more environmentally friendly.

 

Just my two cents anyway.

[Tcrumpen]

Premium petrol supposedly burns more efficiently meaning you're getting more ompft per gallon, however i don't think it's worth the extra cost per gallon, just change your driving style a bit and you'll get comparable results, slower acceleration, not revving the nuts of it, drive in the highest gear that the car can comfortably do. So don't be in 6th gear at 30mph you'd have to floor it to get to 40mph

[Sleeper PC 2016]

this run is just an experiment. Im gonna cover about 300-320 miles so if the computer is right there should be around 100 miles left on the tank

[Levent]

compression ratio is fixed, you dont gain anything by using 98 octane (unless it's a aspirated car with flexfuel thing) fuel on a car that needs 90 or even 89 however lower value than manufacturer advices, you will get knock.

[Dylanc1500]

The compression ratio is why you got the better mileage. You get much less preignition with higher octane when your compression ratio is that high. I'm running 9.1:1 in my truck and I typically run 91 due to better ignition timing. Also check to see if your premium was ethanol free, a good portion of gas stations run ethanol free 91 octane. Once you start pushing 9:1 87 octane starts to preignite.

[Sleeper PC 2016]

Just now, Tcrumpen said:

Premium petrol supposedly burns more efficiently meaning you're getting more ompft per gallon, however i don't think it's worth the extra cost per gallon, just change your driving style a bit and you'll get comparable results, slower acceleration, not revving the nuts of it, drive in the highest gear that the car can comfortably do. So don't be in 6th gear at 30mph you'd have to floor it to get to 40mph

i got 5 gears and i only use 5th above 45 mph. I drive fast and city mpg is 26 with me driving. My dad who drives slower gets 30-33 in the city and 35+ on the highway. He broke 36 one time

[Tcrumpen]

Just now, Sleeper PC 2016 said:

i got 5 gears and i only use 5th above 45 mph. I drive fast and city mpg is 26 with me driving. My dad who drives slower gets 30-33 in the city and 35+ on the highway. He broke 36 one time

That still pretty low, i can quite easily get to 50 - 55 mpg in my 1.2 Turbo Charged Seat Leon going at motorway speeds (70mph)

 

Of course it depends on your engine size, but a civic should get into the 30 mpgs easily

[Sleeper PC 2016]

Just now, Dylanc1500 said:

The compression ratio is why you got the better mileage. You get much less preignition with higher octane when your compression ratio is that high. I'm running 9.1:1 in my truck and I typically run 91 due to better ignition timing. Also check to see if your premium was ethanol free, a good portion of gas stations run ethanol free 91 octane.

i filled up at a shell using their "V-Power Nitro+" fuel

[Sleeper PC 2016]

3 minutes ago, Tcrumpen said:

That still pretty low, i can quite easily get to 50 - 55 mpg in my 1.2 Turbo Charged Seat Leon going at motorway speeds (70mph)

 

Of course it depends on your engine size, but a civic should get into the 30 mpgs easily

i got a 1.8L NA 4 cylinder, your engine is 1 cylinder short and 600cc's smaller. The old civics back then were actually light enough to get 40+ mpg on the highway and 35 city

[Tcrumpen]

Just now, Sleeper PC 2016 said:

i got a 1.8L NA, your engine is 1 cylinder short and 600cc's smaller. The old civics back then were actually light enough to get 40+ mpg on the highway and 35 city

Yeah with a 1.8 you won't be getting 50mpg + unless it's a diesel or you're driving like an old man. I'd recommend look at changing your driving style, you may find that changing your style could increase your mpg by a significant amount, watch how your dad drives; he most likely is easier on the throttle and not so bat outta hell about it

[Levent]

3 minutes ago, Sleeper PC 2016 said:

i filled up at a shell using their "V-Power Nitro+" fuel

I did also notice a significant difference with the same fuel, I usually get around 650-700kms with 45 liters but with that one I got up to 770kms.

[Sleeper PC 2016]

Just now, Tcrumpen said:

Yeah with a 1.8 you won't be getting 50mpg + unless it's a diesel or you're driving like an old man. I'd recommend look at changing your driving style, you may find that changing your style could increase your mpg by a significant amount, watch how your dad drives; he most likely is easier on the throttle and not so bat outta hell about it

that's exactly how dad drives and i drive. he shifts at 2000 rpm every gear, i do 3-4k rpm and sometimes at redline if im having fun

[Tcrumpen]

The higher RPM could be what's hurting your mpg, i've read that short shifting can help with MPG

[Sleeper PC 2016]

Just now, Levent said:

I did also notice a significant difference with the same fuel, I usually get around 650-700kms with 45 liters but with that one I got up to 770kms.

i just saw the estimated range go up from 350 miles to 425 miles in like 5 seconds after the computer adjusts. I only covered a couple miles after filling up. im Leaving for madison in a few minutes and ill update it throughout the trip

[Sleeper PC 2016]

Just now, Tcrumpen said:

The higher RPM could be what's hurting your mpg, i've read that short shifting can help with MPG

in my mind short shifting lugs the engine becasue it doesnt have too much low end torque

[Dylanc1500]

7 minutes ago, Sleeper PC 2016 said:

i filled up at a shell using their "V-Power Nitro+" fuel

Then that is most likely what caused the increase in mileage.

[cluelessgenius]

well as said before i think youre always gonna end up paying more still BUT i for one always buy premium but only from one chain of fuel station too for a couple of reasons:

- slightly better gas milage

- in a lot of modern cars actually more power or should i say not less? modern engines will "tunr it down" a notch if the fuel isnt good enough. my english isnt good enough to explain this fully but besaically better fuel means the engine can do its thing like intended and worse fuel might lead to the engine tunring down timings (for lack of a better word) and therfore worse performance

 

- but heres the big one: the additives in the fuel actually clean and maintane parts of the engine. again i cant expalin fully but theres all kind of additive that keep your injectors clean and stuff so your engine will be in a better state than someones engine who only bought the cheapo stuff

 

plus the math is really easy:

my tank is 50ish liter -> i fill it 4-5 times a month

a liter regular costs 1.39€ -> a liter premium is 1.47€ -> thats 0.06€ per liter difference

thats 3.00€ extra per tank filling _> thats 12-15 bucks a month

for a noticable difference in engine behaviour and a longer life of it over all

 

some people might disagree but for me thats not a big deal for the benefits you gest

[Tcrumpen]

6 minutes ago, Sleeper PC 2016 said:

in my mind short shifting lugs the engine becasue it doesnt have too much low end torque

True it doesn't use all the engine's power but provided that you're not flooring it when you change then it might be more beneficial 

[Sleeper PC 2016]

It’s the end of of the day and here is what I found

-the gas mileage increased barely any/no improvement (360 miles)

-the performance at low rpms has increased (possibly because of an advanced base ignition timing and/or more fuel put in the cylinder)

 

it was a good experiment and it’s coming to a close. Next time i take a trip, I’ll run midgrade and see what happens. I did hit 100+ occasionally during the trip.

[SansVarnic]

Just FYI we have a Car Thread ....

[vanished]

12 hours ago, Dylanc1500 said:

The compression ratio is why you got the better mileage. You get much less preignition with higher octane when your compression ratio is that high. I'm running 9.1:1 in my truck and I typically run 91 due to better ignition timing. Also check to see if your premium was ethanol free, a good portion of gas stations run ethanol free 91 octane. Once you start pushing 9:1 87 octane starts to preignite.

What about cars that are 11.5:1 and even 13:1 and say they take regular?  If have to imagine if it was really a problem or if you could really get better performance or efficiency going higher, they would say so.

[FlatBrokeRacing]

12 hours ago, Dylanc1500 said:

The compression ratio is why you got the better mileage. You get much less preignition with higher octane when your compression ratio is that high. I'm running 9.1:1 in my truck and I typically run 91 due to better ignition timing. Also check to see if your premium was ethanol free, a good portion of gas stations run ethanol free 91 octane. Once you start pushing 9:1 87 octane starts to preignite.

Compression ration does get better fuel economy, its all about combustion efficiency and torque. 9:1 static compression is not high, and not the most efficient, depending on cylinder head and camshaft it will do pretty good. Virtually every vehicle from 2010 down cannot differentiate between fuels. And even up to current vehicles can only distinguish alcohol content. IMHO in your case you are not gaining anything power/efficiency wise from running anything more than 87 octane.

12 hours ago, Tcrumpen said:

Premium petrol supposedly burns more efficiently meaning you're getting more ompft per gallon, however i don't think it's worth the extra cost per gallon, just change your driving style a bit and you'll get comparable results, slower acceleration, not revving the nuts of it, drive in the highest gear that the car can comfortably do. So don't be in 6th gear at 30mph you'd have to floor it to get to 40mph

No premium petro does not burn more efficiently, or cleaner. Octane rating is the resistance to burn, higher the octane, the harder it is to ignite the fuel. 

6 minutes ago, Ryan_Vickers said:

What about cars that are 11.5:1 and even 13:1 and say they take regular?  If have to imagine if it was really a problem or if you could really get better performance or efficiency going higher, they would say so.

To my knowledge there are no vehicles that are static 13:1 compression off the assembly line, and most of the vehicles that are in and around the 11:1 compression ratio are generally ALL direct injected which brings into a whole other ball park of combustion efficiency. "not" having fuel floating around in the cylinder waiting to be ignited by the spark plug means no concerns of pre-ignition happening which means vehicles can be run with lower octane fuel. However MOST manufacturers that have said engines (higher compression ratio, turbo/supercharged, etc) all RECOMMEND a 91 octane fuel, but vehicles can be run off of 87 octane.

 

The reason you are seeing slightly better fuel economy with PREMIUM fuel, is due to one very simple fact. EHTANOL CONTENT, all regular/midgrade pump gas fuels are required to have a minimum up to a maximum of 15% Ethanol content. Ethanol is corn based alcohol, and alcohol has less energy per given amount of fuel, and in order to make the same amount of energy requires more of it. **MOST** Premium fuels (Shell, Co-op, Petrocanada, etc) have premium fuels that do not have ANY Ethanol blends. Unless you start going to Husky in which 94 octane is available (91 octane with 15% ethanol content).

 

So there it is in very simplistic and short form for everyone as to why most premium fuels will get better economy than regular gas.  

[Zodiark1593]

The additives used for increasing octane actually reduce the specific energy of the fuel by a slight amount in exchange for reduced likelihood of detonation (knock), meaning running a high octane in an engine that does not take advantage will actually yield poorer fuel economy.

 

The only alterations that may occur in the combustion process in regards to fuel octane will be to ignition timing. Though if this is indeed the case, this means the engine already has knocking issues (carbon buildup can cause this), or is using fuel that is below required spec.

 

25 minutes ago, Ryan_Vickers said:

What about cars that are 11.5:1 and even 13:1 and say they take regular?  If have to imagine if it was really a problem or if you could really get better performance or efficiency going higher, they would say so.

These type of vehicles utilize special measures to reduce temperatures of the intake charge, and to evacuate the hot exhaust gasses mor thoroughly. Lower temperatures reduce likelihood of knocking, allowing the use of higher (read: more efficient) compression ratios. Some cars "cheat' with clever variable valve timing to obtain the efficiency gains, but lose out on power (Prius). The latter method simulates the Atkinson cycle, and allows the higher physical compression ratio without additional cooling or octane.

[FlatBrokeRacing]

28 minutes ago, Zodiark1593 said:

The additives used for increasing octane actually reduce the specific energy of the fuel by a slight amount in exchange for reduced likelihood of detonation (knock), meaning running a high octane in an engine that does not take advantage will actually yield poorer fuel economy.

 

The only alterations that may occur in the combustion process in regards to fuel octane will be to ignition timing. Though if this is indeed the case, this means the engine already has knocking issues (carbon buildup can cause this), or is using fuel that is below required spec.

Using 91 octane in a vehicle which does not require it will not harm fuel consumption, the reasoning behind this is the specific gravity of the fuels and the "motor octane" of the fuels are too close together for there to be a noticeable difference.

 

Not going to delv into the other side of your factors here. but there is alot more alterations than just ignition timing (intake air temperature, coolant temperature, oil temperature, elevation, general health of the engine all play factors as well as many others).

 

31 minutes ago, Zodiark1593 said:

These type of vehicles utilize special measures to reduce temperatures of the intake charge, and to evacuate the hot exhaust gasses mor thoroughly. Lower temperatures reduce likelihood of knocking, allowing the use of higher (read: more efficient) compression ratios. Some cars "cheat' with clever variable valve timing to obtain the efficiency gains, but lose out on power (Prius). The latter method simulates the Atkinson cycle, and allows the higher physical compression ratio without additional cooling or octane.

there are no special measures for reducing intake temperatures, or exhaust gasses. Variable valve timing is one of the big factors in moving the torque curve around in order to make more low end torque on small engines without sacrificing high RPM horsepower, this plays into efficiency but is not the real answer. Modern vehicles can get away with higher compression due to direct injection.