Too much octane doesn't help and can actually hurt; it burns more slowly than the engine was designed for.

 

I don't know if that is real world accurate.

I usually run 91 octane but I had to run 1600 miles in 2 days so I figured I would run a tank or 2 of 87 octane to see what happened. I found that I got better mileage with the 87 to the tune of about 2 to 3 mpg. If I want performance I run 91 or higher but if I am going to drone on the freeway I will be running 87 from now on.

 

I found in my last two vehicle that gas mileage increased after about 3K to 5K miles. The 05 Camry we traded for our new TL got about 25 city and 32 highway when it was new, when we traded it, it was averaging about 30 city and we could get 40 mpg on a long trip, and that's traveling at 75 mph! My Nissan Frontier only averaged 15 mpg on my daily comute (mostly city driving) and I'm getting 17-18 mpg on the same commute now with 15K on the odo.

We got 20 mpg city out of the first tank on our TL, but like others have suggested, I suspect the dealer probably filled it with 87 octane. I just topped it off yesterday with 93 octane, so we'll see if it improves any. As I mentioned previously, I don't expect much of an improvement till we have about 5K on the odo!

 

Not sure if understand exactly what your saying, but that doens't sound like a fair comparison! Did you also run two tanks of 91 before or after running the 87 for comparison, under the same driving conditions? If your mileage for the tanks of 91 were mixed city/highway, and the mileage from the 87 were straight highway, then I can understand why it was better. But, I bet if your did the same trip using 91 you'd see the same or better mileage.

 

6MT + AEM CAI + open road = $hitty mpg...but awesome drive!!

 

This is copied and pasted DIRECTLY from Acura's Owner Link web site, for those of you who use octanes higher or lower than 91:

Does it help to use a fuel with a higher octane rating than required in my Owner's Manual?

Refer to your Owner's Manual for the pump octane number recommended for your Acura. Use of a lower-octane gasoline than recommended can cause a persistent, heavy metallic rapping noise in the engine that can lead to mechanical damage.


There is no advantage in using a fuel with a pump octane greater than that recommended in your Owner's Manual.

 

Ok, perhaps I wasn't clear but anyone driving 1600 miles in two days is not driving in the city.

1600 freeway miles
4 tanks of gas
2 with 87 octane
2 with 91 octane

The 2 tanks with 87 averaged 2 to 3 miles more per gallon than the tanks with 91 octane.

You would have lost the bet.

 

i get about 450kms out of a full tank so it think it would be converted to 337.5miles, its not so bad considering city driving at 90% and 10% highway

 

I guess I did! Good thing I didn't put money up, but I guess I do owe you a cold beer! Everything I've read made me think the 91 octane would have produced better ileage, Thanks for clearing that up!

 

When all I do is drive back and forth to work(4 mile roundtrip) and run errands I am lucky to get 280-300 out of a tank and usually average about 22-23. Had to travel across a couple states for work last week and I managed to get 468 out of a tank... 34.666 mpg. I was real happy with that.

Driving to florida in a couple weeks, I'm setting a personal goal of 500 on a tank. I'm thinking she can do it.

 

I will admit my test was less than scientific as there could have been more wind with one tank versus the other. I can't say for certain that it was just the gas. I will not disagree with those folks that find they get better mileage with higher octane. I think it depends quite heavily how you drive as well as what kind of driving you typically do. I am very easy on the throttle and like to see those tanks where I average over 30 mpg. On this trip my low tank averaged 29mpg and my high was 32.

I still believe there will be times when 91 octane could provide better mileage but for low load freeway cruising 87 works just fine for me.

 

Excel Spreadsheet in HTML format

This is my milage spreadsheet since my car was new with 21miles to start off the lot.

It also shows before / after oil change mpg's with my calculation and MID calculation mpgs.

**one more thing, 90% of the tanks were driven until the light came on, and the amount to empty shows in the "Miles left" column

*** that last two were only partial fill ups due to such expensive gas fill ups, so I put in .01 in "gal left"

 

The trip computer in mine is constantly saying 21 mpg. I think it just does a brute, mile/gallon calculation. Whereas in the Merc ML320, you can see the gas consumption in real time. As in, you press the gas pedal you can see the values change.

 

It's an average. There's no instantaneous function on the TL.
When you reset the trip computer by holding down select for a few seconds, it zeros the history the calculation is based on. It'll change around a little after you do this until it settles on the average.

 

If you have the NAV you can hack the system and get a trip computer. If you've got it, it's worth the effort, it gives MPG on the fly and an average.

 

To be honest, the MID is pretty accurate, but it is off about 1mpg less then it actually is from my excel sheet.

 

I do have a NAV and how do you go about doing that ?

 

Go here and start reading. https://acurazine.com/forums/car-parts-sale-361/wtb-stock-intake-gen-1-a-145426/

It's really easy to do once you figure everything out.

 

Gas mileage in the TL varies greatly depending on traffic and speed. Traffic also varies greatly city to city.

The type of city driving I usually do gets me 15-16 mpg. If I spend time on freeway I get low 20's. All freeway gets most of us 30-36 mpg. Trip computer is actually very close to accurate in mine for over 30,000 miles.