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Couple days ago I just bought a used 2018 volt with about 42000 miles. I activated OnStar and connected it to myChevrolet app, and I learned that the former owner has only ran 4000 miles on ICE.

The EV range lives up to expectation of 53 miles, but the MPG is only 35-37 when running on free way. I thought it’s supposed to be 42 mpg on free way when using only gas?

Tonight I decided to do an experiment on this car. When I started the engine, I put the car on hold mode so that I can drive using only gas.

I reset trip B to 0 and started driving local for about 9 miles before I merged onto freeway. At this point I got 44 mpg. After I got onto freeway, the reading of mpg kept dropping all the way down to 35 after I drove ~20 miles on the free freeway.

I live in California, and I didn’t have fan or A/C on. Is it normal to have low gas mileage when driving on freeway? I am a little disappointed because they advertised 2018 volt is 43 city/42 highway mpg (on gasoline engine/generator).
 

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Tire pressure? Speed? Outside air temp? All these (and more) cn affect gas mileage.
 

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The ICE gets the best MPG at 45 mph. In my experience, if you're going 75 mph, you'll get around 40 mpg. Also, as Steverino pointed out, underinflated tires can lower gas mileage.
 

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For one, you can't base your mpg on a single 20 mile drive, you barely got the engine up to normal operating temperature, you didn't even use a gallon of gas, as Steve said there are so many variables that affect mpg. Drive it and enjoy it, still FAR better mileage overall than pretty much any gas car.
 

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If you display the Energy screen you can observe the near real time MPG when the ICE is running. In my experience with my 2017 Volt the MPG numbers will not get above 40 MPG until you have driven at least 10 or more miles, highway speed, so the engine has reached full operating temperature. Also, winter blend gasolines will result in lower MPG. Some days I would see barely 40 MPG, other days almost 50 MPG. The Volt's engine management system is probably continuously adjusting the engine timing, air/fuel mixture to prevent engine knock while taking into account temperature, speed and engine load to yield the lowest exhaust emissions.
 
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I have a 2018 Volt and I get about 37mpg at 75mph. At first I was a little disappointed then later in mixed city and freeway I got 42mpg. I am usually operating it as an EV though so I don't measure gas mileage much as this car is my daily commuter. At 75mph, 37mpg isn't that bad really. Driving at 75mph reduces EV range a lot also.
 

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Even a slight up slope in elevation can reduce mpg a lot as well.
I agree, at 75 mph in the Volt, 37 mpg is within normal range.
I have gotten that in my 2018 when I was going that fast on flat or very slight uphill.

The gas mpg is not the volts super-power, it is the 50+ miles of pure ev range. :)

These plug-in hybrids you hear that get 50mpg are not really pure-ev when in ev-mode.......
the gas engine can pop on when you want a lot of power for say, entering the freeway.....
which I think is a major disappointment.......
the Volt does not do that, which is a major plus.
 
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Couple days ago I just bought a used 2018 volt with about 42000 miles. I activated OnStar and connected it to myChevrolet app, and I learned that the former owner has only ran 4000 miles on ICE.

The EV range lives up to expectation of 53 miles, but the MPG is only 35-37 when running on free way. I thought it’s supposed to be 42 mpg on free way when using only gas?

Tonight I decided to do an experiment on this car. When I started the engine, I put the car on hold mode so that I can drive using only gas.

I reset trip B to 0 and started driving local for about 9 miles before I merged onto freeway. At this point I got 44 mpg. After I got onto freeway, the reading of mpg kept dropping all the way down to 35 after I drove ~20 miles on the free freeway.

I live in California, and I didn’t have fan or A/C on. Is it normal to have low gas mileage when driving on freeway? I am a little disappointed because they advertised 2018 volt is 43 city/42 highway mpg (on gasoline engine/generator).
Your numbers is ok. The 42 number is about 55 mph on the freeway. The car is pretty linear on its gas. Upping the speed to 70 will drop the mileage to 40 or maybe even a bit below. The numbers are based on a standardize government test for comparison purposes only. How you drive is also a big factor.

Dale
 

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Your MPG sounds about right as I drove all the way to Mexico going through Arizona new Mexico and texas and back from California. 42mpg is combined but realistically its 35-37.
 

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Even a slight up slope in elevation can reduce mpg a lot as well.
I agree, at 75 mph in the Volt, 37 mpg is within normal range.
I have gotten that in my 2018 when I was going that fast on flat or very slight uphill.

The gas mpg is not the volts super-power, it is the 50+ miles of pure ev range. :)

These plug-in hybrids you hear that get 50mpg are not really pure-ev when in ev-mode.......
the gas engine can pop on when you want a lot of power for say, entering the freeway.....
which I think is a major disappointment.......
the Volt does not do that, which is a major plus.
I agree that's the only thing I ever used my volt for. when in gas mode oh boy all I said was you had a chance to make me a buyer and that right there is what killed it for me. good car ev mode but once gas kicked in I guess the strangest things would happen and became a letdown Uphill has momentum and if you lose it the recover speed was super awful. Noisy engine when my foot was on the pedal in the hills of the 10 freeway i said please don't explode on me, I'm in the desert. but 20 bucks for a full tank wasn't that bad. drop 20 and drive that was fun no frequent oil changes. I wonder if 2019 they fixed anything besides the charging speed
 

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I agree that's the only thing I ever used my volt for. when in gas mode oh boy all I said was you had a chance to make me a buyer and that right there is what killed it for me. good car ev mode but once gas kicked in I guess the strangest things would happen and became a letdown Uphill has momentum and if you lose it the recover speed was super awful. Noisy engine when my foot was on the pedal in the hills of the 10 freeway i said please don't explode on me, I'm in the desert. but 20 bucks for a full tank wasn't that bad. drop 20 and drive that was fun no frequent oil changes. I wonder if 2019 they fixed anything besides the charging speed
When going uphill, you should be in Mountain Mode 15/20 minutes before to get a good 4 to 2 bars in the battery (Gen I or II). First time I did that, I was passing everything in sight including a new SUV that was struggling. Did the same run another time with battery low and it struggled up the same climb (did it but didn't have the acceleration of before). It's called Mountain Mode for a reason but you've got to have the battery prep'ed before hand. If you don't know you are going into the mountains beforehand, then you have bigger problems.
 
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The ICE is not even broken in yet!!

My '17 has 79k+ miles on it. About 20k on gas. Lifetime mpg on gas is right at 40mpg which seems about right considering I lived in a cold climate, run snow tires, occasionally tow a small trailer, and am in ERDTT most days between Nov and March.

I occasionally see over 48 on long trips, but that's staying under 70.
 

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My 2017 Volt has a lifetime mileage of 43. I am mostly below 70 mph and I never drive faster than 73 (since I have not been anywhere yet with a speed limit above 70). I drove from Thousand Oaks to LAX and back twice and set the cruise control at 68 (speed limit is 65). I got 43 mpg on one trip and 42 mpg (rainy day) on another. Speed doe really effect the mileage, so I prefer to keep the speed down and the mileage up. In my previous ICE cars I would drive 5-8 mph over speed limit, but in my Volts (I also had a Gen 1) I only go about 3-5 mph over speed limit. I hit 60 mpg once on back roads going 40 mph with it being mostly down hill or flat, but that is cheating a bit. At 55 mph I have gotten as high as 50+ mpg, but it was on flat lands with the temperature about 80. I like to have my tires at 40 psi also. Most of my driving has been in northern Ohio which is fairly flat. I notice hills have a big effect on mileage both up (low mileage) and down (high mileage).
 

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In my 2017, I have taken many trips from Boston to Ithaca NY and back, which is about 360 miles one-way and mostly fairly flat. I get 42-47 mpg depending on speed 65-70 and direction of travel. When starting the ICE, it can take quite a while to build up the avg mpgs, so 20 miles and various other unspecified conditions such as elevate challenge, etc. it would be very difficult to get much of an accurate reading and it would likely be much lower than you would get on a true road trip.
 

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Couple days ago I just bought a used 2018 volt with about 42000 miles. I activated OnStar and connected it to myChevrolet app, and I learned that the former owner has only ran 4000 miles on ICE.

The EV range lives up to expectation of 53 miles, but the MPG is only 35-37 when running on free way. I thought it’s supposed to be 42 mpg on free way when using only gas?

Tonight I decided to do an experiment on this car. When I started the engine, I put the car on hold mode so that I can drive using only gas.

I reset trip B to 0 and started driving local for about 9 miles before I merged onto freeway. At this point I got 44 mpg. After I got onto freeway, the reading of mpg kept dropping all the way down to 35 after I drove ~20 miles on the free freeway.

I live in California, and I didn’t have fan or A/C on. Is it normal to have low gas mileage when driving on freeway? I am a little disappointed because they advertised 2018 volt is 43 city/42 highway mpg (on gasoline engine/generator).
You have just discovered that wind resistance increases as the cube of speed while rolling resistance increases only directly with speed. Therefore, the fuel economy drops at higher speeds. Whether you are going with or against the wind plays a major role, too. In most gasoline-powered cars, the fuel economy drop is not as noticed since the efficiency of the engine improves a bit as the percent load increases, up to about 75% of design horsepower. However, the Volt is designed to keep the engine running at peak efficiency for any given load so that the higher power requirement at higher speed is more apparent. Nothing at all wrong with your Volt!
 

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You have just discovered that wind resistance increases as the cube of speed while rolling resistance increases only directly with speed. Therefore, the fuel economy drops at higher speeds. Whether you are going with or against the wind plays a major role, too.
The amount of force needed to move a car at a constant speed basically doubles between 50 MPH and 70 MPH. You need twice as much force at 70 MPH and that force requires energy. You want great mileage? Drive slower. Of course the car's aerodynamics, the tire rolling resistance, the wind direction will all play a role in the actual number for a specific car.
 

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Does the Driver Information Center tell you how many miles it's been driven on ICE, AND the total gallons of fuel used?
OH, that, yes, I am aware of that and use it.
That works well on a per-trip basis.
I was wondering if there was a rolling lifetime total, which it seems there is not, unless you use a 3rd party app.
 

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Where can you find the car's lifetime gas mpg?
There is no display in the Volt showing the total ev miles/total gas miles breakdown. There is an energy usage display on the center console that provides a Lifetime MPG number. There is no Lifetime MPGcs display (gas mileage when using gas).

You can use that Lifetime MPG number and the odometer reading to calculate your Volt’s lifetime gas consumption, in gallons. If you have access elsewhere to the total miles/total ev miles split (see below), you can calculate your total gas miles, then divide by gas consumption to get MPGcs gas mileage when using gas.

If the lifetime MPG showing on the energy usage display is less than 250+, math says the approximate lifetime consumption of gas = (miles on the odometer/MPG =) X gallons of gas. (Note: that works only if the lifetime MPG has not been reset by a service dept or by an app - some who buy a used Volt choose to reset it.)

If you have an active OnStar account, even the "free" one ("Connected Services" is one such account), you might be able to get the total miles/ev miles breakdown from the mychevy.com website. If your Volt is registered on voltstats.net (a forum which is closing down this April), you can obtain the total/ev miles breakdown there, as well as the MPG and MPGcs numbers. You can also download your Volt’s statistics that list the MPG to 4 decimal places. Total miles - total ev miles = total gas miles. Total gas miles/total gas used = MPGcs gas mileage when using gas.

You can also use the total miles/MPG = total gas used to get an approximate breakdown of total ev/gas miles. Multiply total gas used by your gas mileage (if you know it, or use the window sticker rating of 42 mpg for Gen 2, 37 mpg for Gen 1) to get total gas miles. Then subtract that from the total miles to get the ev number.

By the by, the lifetime number of gallons of gas consumed is also the number of ev miles you must drive without using any gas to get the lifetime MPG to increase by 1.0000.
 
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