Not getting the magical mileage that is advertised for this car.

[Grumpy Bear]

I had this 2006 Honda Civic that had been in the family since new. 32 mpg was the worst it ever did and that was my sister-in-law (my brothers wife) driving it 85 mph for hours. My worst winter numbers were closer to 34. Summer this was a 40 mpg car.

I let my wife's brother use the car while in town in the early fall. He treats every car like he stole it. Left it near empty in a parking lot. 25 mpg!! I have no idea what he did that car, but it was the last time he was ever allowed to drive anything with my name on the title.

[daleWV]

akawendystorm maybe a neighbor has been stealing a gallon or two out of your gas tank here and there to run his lawn mower or snow mobile?

[Grumpy Bear]

So I bought this car a month or so ago. A 2015 with 67000 miles. My way to work is 9 MI 6 of witches highway. And my MPG has been all over the place. My lowest has been 31, and my highest average has been 38. Total of an averaging 34 or 35. it seems that the smallest changes in wind affect mileage and cold weather affect mileage also. These are not computer estimates these are top off at the pump calculations.

I did install roof racks but I might take them off to see if it helps a bit. I don't think it would affect it this much.

I'm disappointed. Today I went to pick up my daughter and the route there is 50 miles an hour almost no stops for 10 MI. And my computer averaged it out to 40 miles per gallon. Which is great, but considering it's 50 miles an hour I should be getting more than 40 MPG which is what stated for highway mileage from the EPA.

I guess I should state that I live in a part of Washington state that doesn't have a ton of flat area and there's usually a little bit of wind sometimes a lot of wind. (Oh my God this car has terrible noise with side winds.)

I feel like a Toyota Corolla could have gotten better mileage than this with the 4-cylinder. honestly I wouldn't have bought this car if it wasn't for the advertised amazing mileage. If it wasn't for a mileage nobody would buy this car lol.

Where do I need to start to figure out what's going on here? Thank you

You live in a spot that is going to be a challenge to make EPA numbers. I don't think there is a 'Billy goat' cycle for the EPA test. You may never reach those numbers, but neither would any other manufacture in that environment. So first adjust your expectations. Reach for improvement instead of a number. That said there are several things to check and to learn.

Factory alignments are notoriously terrible. In spec but not on spec. These cars have HUGE castor numbers to going straight down the road is pretty much a given even with the other numbers fighting it. Mid spec will be close to zero camber, zero toe. Given your wind situation perhaps up to a quarter degree negative camber (front) with a hint of positive toe. Rear axle needs to be at least in spec. It's a warranty issue if it is not.

You have two numbers for tire pressure. The door plate value and the maximum inflation pressure printed on the side of the tire. That one printed on the tire is a HOT number not a cold inflation pressure. Sneek up on it and monitor and then stay on it. Each 10 degrees is about 1 psi. If possible do you checks late morning in the shade.

Get yourself a Scan Gauge III or similar device and train yourself. Your habits are HUGE in fuel economy. Think of it as Biofeedback.

Especially in the winter your oil choice is a big player in fuel economy. Not all 0W20 oils have the same low temperature performance. Low CCS test value. You might not run at -35 C but your motor will need to get from whatever the ambient temperature is to fully warm, and the slope is NOT linear. This number is more important than the VI for cold weather performance.

Example O'Riley's 0W20 CCS tested by PQIA 5,996 cP
Mobil 1 AFE CCS tested by PQIA 3,928 cP

See the API requires a MAXIUM of 6,200 cP at -35 C but there isn't a minimum

[Eggman]

So I'm in Canada and just bought a 2024 Mirage GT based on the claims of the fuel efficiency and not wanting to have a second car being a major emitter (our other is a hybrid Tucson).

I have 1300 kms on the car now since September and I am not seeing anything near advertised claims of fuel efficiency. I'm driving it like a baby keeping the eco light on as much as possible. No wind. No racks. No reason. Not that many hills. Tires are inflated. We hardly drive the thing and never idle it.

I'm averaging around 300 km to a tank, maybe 340 if I push it. It's a 35 L tank. That's work than 10 Litres per 100/km. I dont know how that translates to MPG but There are 4 litres in a gallon so I guess that works out to 24 mpg or so. The car was advertised to give 6.6 L/100 KM in the city, 5.6L/100 KM on the highway, and 6.2L/100 KM combined with CVT. Currently my Hybrid Tucson is outperforming this little car even with racks, roof box, and dare I say it, towing a 1200 lbs trailer behind it. It's criminal!

Is there anything one can do when you are getting about half the advertised mileage on a brand new car?

Cold winter temperatures and short trips (not long enough for the engine to hit full operating temperature) will produce poor fuel economy. These cars run their most efficient when it's warmed up.

Ways to address this is to get an engine block heater to help warm the engine faster and hold out for summer weather.

And please report back when your fuel economy improves.

[defensivetackle99]

Cold winter temperatures and short trips (not long enough for the engine to hit full operating temperature) will produce poor fuel economy. These cars run their most efficient when it's warmed up.

Ways to address this is to get an engine block heater to help warm the engine faster and hold out for summer weather.

And please report back when your fuel economy improves.

Your 1st point is exactly why I, for example, right now, am getting 25-35 MPG in winter city short+idle flat commute aka 3 mile trip from home to the store and vice versa, even keeping the PSI at 35 and the RPM at or below 2,000 RPM. That trip takes 8-10 minutes to accomplish. The Mirage, and any ICE vehicle, really, is not meant for that condition from my perspective. To improve my MPG, I had to take a longer route. All about having realistic expectation.

[Grumpy Bear]

Your 1st point is exactly why I, for example, right now, am getting 25-35 MPG in winter city short+idle flat commute aka 3 mile trip from home to the store and vice versa, even keeping the PSI at 35 and the RPM at or below 2,000 RPM. That trip takes 8-10 minutes to accomplish. The Mirage, and any ICE vehicle, really, is not meant for that condition from my perspective. To improve my MPG, I had to take a longer route. All about having realistic expectation.

Block water heater helps for service like that.

So can these: https://www.hotstart.com/product-sea...-heating-pads/

Oil in service like this gets a very high water load. Much shorter OCI's.

[geejoguy1]

Don't know about cvt, but with a mt I make sure I keep the green eco light on and average 45 mpg winter or summer.