Rogarven

I went back and looked at the owners manual and it states that it recalculates when the gas cap is opened. I am in TX, BTW. However, I probably will still use the old fashioned way of doing mileage. Wife and I are pretty strict about that.

jcat_350

It doesn't need the injector cycle, the fuel pump is a fixed volume (i.e. gallons/liters per hour). It then guesses based upon how many 'hours' the car has run for and how many miles you've gone. That's why they're inaccurate.

However, if it did as you say and used the injector cycles, it would be much more accurate. Problem is every car would need a Terabyte HDD just to store that amount of info

mlacomb

That first part can't be correct. A car will use less fuel at idle for an hour than going 60 miles an hour for an hour, right? The fuel pump doesn't cycle - but I'm sure there's something like a bypass that is able to keep the fuel at the correct pressure in the rails. The car has to know the injector cycle to know how much fuel is going into the cylinders, and that would be a very simple calculation. This wouldn't take a lot of memory, because the MPG calculation can be done over time and "added to" rather than having to keep the entire table in memory.

For example - and this is just a made up example, I don't really know how much fuel our injectors use. Let's say we have an 8gph fuel pump. If each injector had the ability to use a gallon of fuel per hour when on constantly, you'd use 6 gallons an hour. But at 1/6 duty, the engine would use only one gallon per hour, not the 8 gph that the fuel pump could provide.

igzy

Alright, so yesterday I broke down and decided to put in regular gas So far I can tell two things: 1) the throttle response is not as quick as before (could be my butt-dyno inaccuracy) and 2) fuel consumption didn't change (based on the car computer - will confirm on the next fill up). I will do a few more tanks just to make sure that the long term fuel trim is adjusted to the new octane (ign angle). As for response, I'll just step on it harder

greenchile

I'm certainly going to try regular at the next fill-up just out of curiosity to see if I can tell a difference with response, fuel economy or pre-ignition. My last 3 vehicles ('98 Honda Accord, '99 Toyota Land Cruiser, '11 Hyundai Sonata) have all had pre-ignition/pinging under heavy load when I put the regular in it. I live at 5,000 ft elevation so our Octane numbers are 86, 88 and 90/91. I've just decided that I'm willing to pay the extra $3 - $4 for the premium per gas tank and not have to worry about the pre-ignition/pinging. That's less than the cost of a Subway sandwich to ensure I'm getting the most efficient burn and no detectable pre-ignition.

igzy

Yeah, in your situation due to elevation I would do the same. My former Nissan Maxima would also ping with anything less than 91 octanes and I am at sea level. I pushed the ES a bit yesterday under WOT to see if it would ping and it didn't. I am yet to go up a steep hill under WOT, that's where Maxima would ping with low octane, to see if ES would...

Btw, yesterday savings for me were 60 liters x $0.14 = $8.40. The difference from regular to premium here is $0.13-0.17 per liter, i.e. avg 12% mark up over regular so is significant. Works out to about $400 in savings per year based on current gas prices and 30,000 km/year of driving at 9L/100km rate. I know that in US the % difference is much smaller between prem and reg...

LexBob2

Around me the difference between regular and premium runs .40 to .50 per gallon depending von prices at the time.

christcorp

Where I live, 85 octane is $2.99. 87 octane is $3.09. 91 octane is $3.19. Per Gallon

rickster9

Well my cars been off the lot for awhile now and I'm up to 18.5 on my 2010. Like I said both 2010s on the lot said the cars were averaging 13.5 mpg and since the cars idle on the lot alot that may say something about how the computers operate. Then again people tend to floor the car when they it and I would imagine the computer would compensate for when you're moving. The manual says premium is "required" not recommended.

For those who say it's pennies a day, it really isn't. Where I'm at it's a 45 cent a gallon difference. Do the math..

Is the '10 engine the same as on the Camry or was that just 2007 - 2009?

Also is 18.5 "computer mpg" similar to what you all are getting?

Thanks

Rogarven

What about Mid-grade or 89 oct? Would that be a compromise? FYI, when I was in CO this summer in my 05 DeVille, I did put premium in it even I normally put in regular. It has the Northstar V8. I felt that going over the "million dollar highway" from Durango to Silverton and Ouray, it was worth it. Got great milage too for a V8

LexBob2

The engine in the 2010 is the same as in 2007-2012. It is also the same in the 2013-2014. No changes. Pretty tried and true after 8 model years.

jcat_350

Yes, it really is. You shouldn't be letting the car go below a quarter tank. In my 07, to fill from a quarter tank takes about 15 gallons.

15 * .45 = $6.75 per tank.

Then it becomes a question of how long a tank lasts you? Personally, I can go about 10 days on a tank. That makes it 67.5 cents per day, if I was to use premium (91 or 93) which I don't.

I use 89 octane and the car distinctly runs better. 89 octane is about 15 cents per gallon more than 87 where I live.

15 * .15 = $2.25 per tank. Divide that by the 10 days I get out of a tank, and it's 22 cents a day to have my car run smoother and quieter, get (slightly) better MPG and be more responsive.

christcorp

Exactly my point JCat. Even under worse case scenario, like Rickster, where it's $0.45 a gallon more; A totally empty tank would only be $8.00 more. And as you correctly pointed out, if a FULL tank lasts 10 days, that's still only $0.80 a day.

But what really matters is: "How does the car handle the higher grade gasoline"? If it doesn't sound better, drive better, better MPG, etc... then it's totally silly to pay the extra $8.00 per tank. But if the car improves in ANY manner at all, then that $8.00 per tank will almost vanish. This is where people don't understand economics. JUST 1 MPG IMPROVEMENT makes a major difference. Using the average of 20 MPG in town; 18 gallons is 360 miles. 1 MPG improvement means 378 miles. 17 miles more. Which is almost an entire gallon of gasoline for FREE. Meaning, you just saved around $3.00. So now, that $8.00 additional cost per tank, just dropped down to $5.00 per tank. And common sense says; if your engine improves on the MPG efficiency, then chances are that the MILE MARK when an expensive significant repair will be required, will be pushed out longer. In other words, less wear and tear on the engine and tranny. And chances are, if you improve just 1mpg in town, that you'll probably improve a little more than that if you drive on the open road.

But again, I always say that each person needs to drive their car for at least 2 tank full in a row of EACH GRADE gasoline. Your car will let you know which one it likes. If it runs equally on 87 and 89 grade and no difference at 91, then use the 87. But if it gets the best MPG and runs the smoothest on the 89 or 91, then that is what you should use. Any extra cost will be negated with MPG and repairs later.

mlacomb

When I lived 7 miles (city) from work, my mileage was about that. Now that I'm 17 miles away in a more sub-urban setting (i.e. getting up to higher speed and being able to hold that speed) I see anywhere from a low of 22 (remote starts and idling kills mileage in winter) and a high of 27.

MCSCOTT

I have always used regular gas (87 octane) and always get good gas mileage.