Ridiculously Low MPG, Whats going on!

[BKK Jack]

I have discovered that my Integra's computer is a little optimistic with regards to the mileage it reports by about 3%.

I try to record the computer reported gas mileage for each tank when I fill up, which allows me to compare the computer calculated mileage to the actual mileage based on actual gallons used. While each tank can be off significantly due to variations at each gas pump, using a sample of a dozen tanks helps reduce that error.

The last time I checked my sample was around 2,000-3,000 miles and the computer's reported mileage in total was approximately 3% too high.

I use Fuelly - used to be aCar - to track mileage and other expenses in my vehicles. I've also noticed that the car is a bit optimistic in regards to mileage by about the same, or maybe even a little more than yours. I have a hard time wrapping my head around why this happens. I haven't traveled anywhere since I bought the car, and only fill up at one of two different stations close to my house. I even try to use the same pumps at those stations to try to reduce fill errors.

 

[Palut]

I use Fuelly - used to be aCar - to track mileage and other expenses in my vehicles. I've also noticed that the car is a bit optimistic in regards to mileage by about the same, or maybe even a little more than yours. I have a hard time wrapping my head around why this happens. I haven't traveled anywhere since I bought the car, and only fill up at one of two different stations close to my house. I even try to use the same pumps at those stations to try to reduce fill errors.

Perhaps manufacturers know the limits of precision in the fuel system sensors and injectors hardware and then program the cars to prioritize the most optimistic data when validating sensor readings? Just a theory, but I can't think of another reason.

I had two WRXs, 2015 & 2018, that also reported optimistic fuel economy numbers, to the tune of 5%-10%. At least the Integra has been better than the WRXs were.

 

[submitaweasel]

I have discovered that my Integra's computer is a little optimistic with regards to the mileage it reports by about 3%.

I try to record the computer reported gas mileage for each tank when I fill up, which allows me to compare the computer calculated mileage to the actual mileage based on actual gallons used. While each tank can be off significantly due to variations at each gas pump, using a sample of a dozen tanks helps reduce that error.

The last time I checked my sample was around 2,000-3,000 miles and the computer's reported mileage in total was approximately 3% too high.

Every vehicle I've had with this feature has been optimistic. The integra has been the most accurate. I normally average about 1-1.5mpg worse than what it shows.

The freak fill up was when we got our first cold snap and it showed I got 29.5 mpg and my fillup calculated to 33.

I've also found I get much better than advertised with a 30mpg average in the city. My car is a 6mt and I always turn off idle stop. I also don't baby it but tend to shift at no higher than 3000rpm (1-2) and keep the revs as close to 2k as possible while cruising.

 

[tyt2lynnin1]

Every vehicle I've had with this feature has been optimistic. The integra has been the most accurate. I normally average about 1-1.5mpg worse than what it shows.

The freak fill up was when we got our first cold snap and it showed I got 29.5 mpg and my fillup calculated to 33.

I've also found I get much better than advertised with a 30mpg average in the city. My car is a 6mt and I always turn off idle stop. I also don't baby it but tend to shift at no higher than 3000rpm (1-2) and keep the revs as close to 2k as possible while cruising.

does turning off Idle stop really help with gas? or turning on and off the engine will actually eat up MORE gas? Makes no sense to me! If you turn on and off something it should take more energy to start again imo. Just trying to do everything to get the best possible MPG!

 

[submitaweasel]

does turning off Idle stop really help with gas? or turning on and off the engine will actually eat up MORE gas? Makes no sense to me! If you turn on and off something it should take more energy to start again imo. Just trying to do everything to get the best possible MPG!

Technically, that would depend on the length that the engine remains off. Yes, it will use negligibly more gas on startup. I mentioned idle stop because technically it should improve the mpgs but I hate it and turn it off in every vehicle I've ever had with it.

Lower rpm = better mpg mpg even with these turbo engines. I don't think I saw you post if yours is a cvt or 6mt. If it's a 6mt keep the rpms down like these new autos do. Light acceleration between 1800 & 2500rpm, avoid boost & high rpms.

 

[tyt2lynnin1]

Technically, that would depend on the length that the engine remains off. Yes, it will use negligibly more gas on startup. I mentioned idle stop because technically it should improve the mpgs but I hate it and turn it off in every vehicle I've ever had with it.

Lower rpm = better mpg mpg even with these turbo engines. I don't think I saw you post if yours is a cvt or 6mt. If it's a 6mt keep the rpms down like these new autos do. Light acceleration between 1800 & 2500rpm, avoid boost & high rpms.

mine is CVT is it still better to keep the auto shut off for better mpg?

 

[RRP RSX-S]

I have the cvt and keep auto shut off off. First few hundred miles I got low to mid 20’s. It it crept up from there. With 6000 miles I average 36mpg now.

 

[tyt2lynnin1]

I have the cvt and keep auto shut off off. First few hundred miles I got low to mid 20’s. It it crept up from there. With 6000 miles I average 36mpg now.

will give it a try thank you!

 

[RB2490]

After a fresh oil change in October. I reset trip and out of 1450 miles I'm getting 31.2 mpg and I don't baby the car at all. I shift at 3500 rpm, always in sport, did those two test videos and each video i did 25-80mph runs about 10 times each. Super happy with the mpg I get. If I baby it I'm pretty sure 34-35 mpg is possible

 

[jd2157]

Every time I get a new car I reset the trip computer and drive til the low fuel light comes on. Then note distance for the tank, note how much fuel it takes to fill, then subtract that from total tank size.

With this baseline, I keep filling when the fuel light comes on and pay attention to how far each tank gets. If there’s a big change I’ll calculate mileage.

Over time you’ll get a sense of the mileage you should get (useful to detect issues), what things affect your mileage (winter gas/tires, driving habits, etc), you’ll also know how much fuel left in the tank when the light comes on and how far it’ll likely get you.

 

[RB2490]

1500 miles after my oil change in October. 31.3 mostly stop and go traffic, and city plus multiple 30-80 runs

 

[tyt2lynnin1]

guys, happy to report back that after I reset it and refilled my first tank of gas, I been getting 33's if I baby it in normal mode, with auto idle on and off. For gas I didnt follow manufactures suggestion though I just went with the the cheapest gas, regular it was. lol. Hope it doesnt do anything bad to it!?

 

[RB2490]

guys, happy to report back that after I reset it and refilled my first tank of gas, I been getting 33's if I baby it in normal mode, with auto idle on and off. For gas I didnt follow manufactures suggestion though I just went with the the cheapest gas, regular it was. lol. Hope it doesnt do anything bad to it!?

It's okay to use 87 in situations where 91 or 93 isn't available but do not race your car with 87. 87 can introduce knock which in short can cause your engine to blow. Knock control creeps up pretty quickly on this car even when on 93, so if your spirited driver and you bang 5000-6500 on the reg your car won't be happy. While in 87/89 I would drive easy

 

[Tony503]

There’s some anecdotal evidence that using 91+ octane in the 1.5T’s that are designed for it gives a few extra mpg (or rather, you lose a few mpg by using regular octane) so most of the extra cost of premium gas is offset by the increase in mpg

 

[BKK Jack]

I'm sure I'm just pouring fuel on the gasoline fire (nyuk, nyuk), but unless I have no choice, I'll never put anything but the highest grade available at the pump into my Integra. Where I live that is 93. Note: I'm pretty sure in CA the highest widely available grade is 91, which is what is "recommended" by Acura for our cars.

I may have allowed myself to fall victim to the scam. Every now and again in these discussions, you'll see someone post that their sister's friend's cousin works for a distributor or a gas station and they claim that there is no difference in grades, because they all come out of the same truck, or something like that. I have no way of knowing if they are actually right, or are sitting in a basement somewhere with a tin foil hat. I choose to believe there is a difference, because if there wasn't someone, somewhere with real qualifications would have called BS by now.

I don't believe that using the top grade gives me better performance or gas mileage in the short term, but I do believe that the highest grade available at the pump contains the most additives to help prevent the build-up of carbon and other nasty things that might reduce performance in the long term and possibly require corrective maintenance. In addition to using the highest grade available, I only get gas at stations that are certified as Top Tier.

https://www.consumerreports.org/fue...r-gasoline-worth-the-extra-price-a7682471234/

One of the things that makes it easier for me to put the most expensive gas into my Integra is my previous vehicle; a Toyota Tacoma Off Road. That hulking beast had a big, lazy V6 that only required 87, had a 20 gallon tank and only got 20 mpg on it's best days. The increased gas mileage of the Integra offsets the per gallon cost of 93 to the point that my per mile fuel cost for 93 in the Integra is actually less than it was with the Toyota. So, in that respect, I'm actually paying "less" for 93.

Yes, I know I could save even more with lower grade gas, but I spent a lot of money for a car with smaller, fairly highly tuned turbo-charged engine and I'm going to do everything I can to treat it right. That will also include oil and filter changes at 5k miles no matter what the oil life indicator says.