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Discussion Starter · #1 ·
Well, I netted 42.8 average mpg at my first tank of gas. It was a surprise to me since EPA rate this car 38mpg at highway; yet my driving including 20% city.
However, this behavior changed after my 2nd tank of gas. I fuel it up at Costco with 87 unleaded last week and so far I am only getting only 37.8mpg average on half tank so far.
This makes me believe the 1st tank number may not be a typical number. I got my first full tank of gas from dealer and I didn't know what they put in.
I am going to fill my next tank with 91 from Costco and to see if I can regain 42+ number. That would be worth it since the price difference between 87 and 91 is only like 6%, if I can go 10% more miles then I will do it from now on.

 

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how are you calculating mpg? If using the onboard diagnostics stop. Use the good ole method of refueling and dividing miles driven by gallons pumped.

So funny you are worried about only getting 38mpg when there is probably only a handful of the 1.8's out of the hundreds of thousands sold that get close to that. The HR16 is a real gas sipper.
 

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just for the record, octane rating isn't going to make a difference in gas mileage without tuning for it. if your car is recommended 87, bumping to 93 isn't going to matter. just run whats recommended. the last tank we got in our versa (1.8L hatch) averaged out to 35 mpg, which is the best i've ever seen from ours. our normal average is 31 ish.
 

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The trip computer in my Altima is a bit optimistic, but idk how much yet.
Also, if you didn't refill to the same level as your previous fill [as LBV said^] then your mpgs will be skewed. If i refill low, the mpgs will calculate artificially high, and if i refill high, then the mpgs will calculate artificially low. That's why it's more meaningful to use an average of more fillups, or more total miles divided by total gallons.
Sorry if i'm confusing, hope it helps:)
 

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Discussion Starter · #8 ·
I guess I will have to wait couple more refuel to get an accurate mpg number.
However, the octant number does affect mpg. When run with higher octant, the same amount of gasoline injection will give a little bit more exhaust gas, if burn completely, hence more torque. When matching with a 4 or 5 speed transmission, it doesn't really show much. However, if matching with a torque sensitive CVT, it will set at slightly higher gear and then get a better mpg that way.
 

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All octane is is the resistance the fuel is to burn, thats why if you put 87 in a higher performance car that calls for like 91-93 you will get a knocking sound, its called pre combustion its the fuel in the cylinder burning on its own not from the spark plug so the noise is from the two colliding wave fronts it can kill an engine. So putting higher octane in when you don't need it will just not burn the fuel as well. I know I did 2 years high school auto tech and to years collage tech training have 3 diplomas and am ford certified. So like it was said before just put what nissan calls for our your just wasting money.
 

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Discussion Starter · #11 ·
One secret you guys don't know:

"On modern engines with sophisticated engine management systems, the engine can operate efficiently on fuels of a wider range of octane ratings, but there remains an optimum octane for the engine under specific driving conditions."

"If you are already using a fuel with an octane rating slightly below the optimum, then using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy."

All are true above, However, US 87 unleaded is probably the lowest octane gasoline around the world. And almost all "world engine" uses some retarded timing for US setting. Thats why you can hear most people tell you when they use higher octane gas, they feel more power; despite the text book theory. This is not some kind of hype, it is real because the gas we have. Car company want to have their popular model use regular unleaded, so they use computer to set the timing a little off. By putting higher octane gas, some engine will put out more power; but not for low compression ratio engine.
 

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Do you have a link to show this "secret"? Also my dakota has 10.1:1 compression ratio and calls for 87 and I have ran every grade of fuel in that and the V and it made 0 difference so do what you want I'm just saying from what iv done and what I have been taught so you go ahead and pay even more at the pumps.
 

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Discussion Starter · #14 ·
A link? There are many article to read about, here is one: Octane Number And Engine Performance

I wrote articles for Asian car magazine at 90s, mainly translate car test reports, sometime my own reports. There are a lot of examples cars in Euro, US, Japan have different output numbers despite same engine. Most of times, US cars put out 5-10% lower power (converted unit). What's at play? Timing.
I had a Stillen ECU for my Z that required 93 Octane, when 93 was popular. Then when gasoline dropped to 91, I had to have Stillen re-program that ECU to run on 91.... Of course with lower performance. My alternative was octane booster. But eventually I gave in.
 

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how are you calculating mpg? If using the onboard diagnostics stop. Use the good ole method of refueling and dividing miles driven by gallons pumped.

So funny you are worried about only getting 38mpg when there is probably only a handful of the 1.8's out of the hundreds of thousands sold that get close to that. The HR16 is a real gas sipper.
I syill don't get how the mr20 is rated better mpg than the hr16 and mr18 with cvt I know I did almost a 500 mile trip with mine and had a quarter tank of gas left.lol
 

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I syill don't get how the mr20 is rated better mpg than the hr16 and mr18 with cvt I know I did almost a 500 mile trip with mine and had a quarter tank of gas left.lol
saying quarter tank of gas is not an accurate measurement. The Sentra has a larger tank. The mpg calculated is the only thing that counts. I myself don't understand the fuel efficiency of the mr20. Actually I don't understand the mediocre fuel economy of the mr18. It's well documented on here that the mr20 powered versa's in fact get better mileage then the mr18's. The combination of the engine power curve and the the transmission must put the rpms in it's sweet spot while cruising or something.

BTW everyone please check off your gas mileage in this thread http://www.nissanversaforums.com/ge...rsa-1-6-1-8-gas-mileage-poll-please-vote.html. Doesn't matter if you have a C11 or N17 Versa. All that matters is the engine. Sorry MR20 guys I didn't think to add a slot for you.
 

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Ok well like I said do what you want belive what you want I have you two links to credible web sitesthat everyone knows about but hey what do they know right? I mean the one you linked to don't even have a known name Im not going to continue this argument online it's pointless.
 

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Discussion Starter · #18 · (Edited)
What Steve Jobs taught us? Stay foolish! That means always keep a open mind and ready to learn.
The world gasoline standard is 98/95 for most of world, which you can find in Euro and Asia. Before 90s, cars use to have different compression ratio if sold in US vs Japan. After 90s, the compression ratio stay the same, just to receive different computer or computer program. After 200x, micro computer became so powerful, they can learn what kind of gas you are using and adapt to it.
 

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Just test the different grades of gas in your vehicle. Report back your findings.
 

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I put premium only once in the Versa and that was when I was in the US. It was cheaper than putting regular fuel here so I gave it a shot. Drove home (1.5 hours), and some city driving. It was the worst MPGs I have ever gotten.
 
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