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Discussion Starter #1
I've got maybe 600 miles on gas in my Gen 2. I've read others say their gas MPG gets better over time. So far, I'm a little surprised that my results are no different than my Gen 1 on the same terrain and temps, even though my Gen 1 did not have LRR tires.

I'm getting 37 MPG highway 70-75 according to the energy info screen. This is the same, if not slightly worse, than my Gen 1 on the same roads, same temps.

EV range has been better than expected. Hit 64 the other day in lower speeds and can even squeeze out 56 on my 80% highway commute.

So did some of you long term owners notice a gas MPG improvement over time? If so, what mileage on gas did you start seeing an improvement?
 

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There are many variables in the gas mileage equation. Headwind vs. Tailwind is a big one especially at speeds above 70 mph. Type of gasoline Summer blend / Winter blend. Elevation changes. Tire pressure and type / brand of tire. I have seen anything from 34 mpg at highway speeds with a headwind to 42 mpg on slower roads in calm warm conditions. My normal measurement would be gas mileage on the freeway cruising at 78 mph. Typically 34-36 mpg.
This in my 2011 with 104,000 miles and running Michelin Primacy MXV4's at 40 psi.
 

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Discussion Starter #4
On the typical trips where you burn gas, how many gas miles are you doing and how many would it have been in your Gen 1?
I do a regular 120 mile round trip for work (no charging)1x week, so I?m now doing a little over half that trip on gas (64 miles) where maybe 80 miles would have been gas on my Gen 1. Seems enough time for the engine to warm up, but I?ve heard Gen 2 sees bigger improvements as the ICE ?breaks in? so-to-speak. Gen 1 vs Gen 2 ICE mpg on this trip has been about the same so far.
 

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Well if you are running regular gas now vs. premium in Gen I you are 20% ahead $wise if the MPG is the same.
 

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I actually wonder if there's something about small tolerances in things like alignment and such that make these cars vary by as much as 10% or more. I had 2 Gen 1 Volts, and the second one especially developed pretty sad stats after a while (for a Volt), like below 35 mpg on the highway, and battery range rarely got beyond the low 30's, even in warmer temps, despite what looked like normal battery output. My ELR does better, like it's not hard to get 40 miles range out of it in temperate weather, albeit with a little bit higher battery capacity, but it also has 20 inch wheels with sticky summer tires, worse aerodynamics, and the dreaded power seats that GM wants people to think are too much of an electric drain to include on the Volt (rolls eyes).

I guess what I'm saying is that your mileage might never improve, and there are some clunkers like my second Volt was. That's my theory anyway.
 

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The first thing to try is holding your speed to 65 instead of 70 -75. If your gas mileage improves, as it should, then everything is probably ok. Contact Onstar the next time you after you have driven on gas for a period of time and ask the OnStar representative if there are any engine computer error codes, then you can contact the dealer with the code information. In a typical ICE vehicle if the fuel economy drops significantly below what is expected the likely suspects are the O2 sensor, PCV valve and the throttle body unit. The Volt's gas engine has these components too and maybe that is the source of the lower than expected fuel economy.
 

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On the typical trips where you burn gas, how many gas miles are you doing and how many would it have been in your Gen 1?
As implied here, if you're only doing a very small amount of miles on gas with each trip, the engine never warms up to optimal and your mileage will be lower. If, instead, those 600 miles on gas all came from one or two trips, you should see higher gas mileage.
 

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There is a break-in period even though GM claims there is not. The engine will start to run smoother and get better mileage over time. I also got a slight increase after changing the oil the first time. (Both Volt and ELR.)

I really don't pay attention to mileage that much any more since I only buy gas every 6 to 8 weeks. :) What's the difference if it's 35 or 37 when you drive mostly on electricity? I do keep my gas purchases in an expense app, so, I do have good stats.

These are actual odo/tank-fill measurements. All daily drivers except the truck. All using premium. All have made long trips:
HEMI truck = 13.35 lifetime.
HEMI Magnum = a whopping 16.89 lifetime.
Volt = 108.13 lifetime
ELR = 104.96 lifetime to date.

I'm pretty happy with my ELR!
 

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I have never noticed a significant gas mileage difference between new vehicles on day 1 vs day 365, but you might want to burn a tank of gas through it. You should be able to match the EPA rating driving about 65 mph on a flat highway with no wind. Make sure you are running recommended tire pressures.

Given that you are used to running Gen 1 on the same route it is interesting that Gen 2 would be less, it should be a bit more. I would watch it for a few tanks of gas just to be sure it isn't that tank. Also, how are you measuring the gas mileage? Might just be a difference in computer estimate or something.
 

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I still only get in the high 30s, or if I'm really lucky, the low 40s when I'm driving at 75+ MPH. I'd say 65-70 is probably the sweet spot where you'll get the best highway mileage. If I'm not on the highway, I've been squeezing 55-60 MPG out of it by being mindful of the engine and trying to coast with the engine off as long as possible.
 

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So did some of you long term owners notice a gas MPG improvement over time? If so, what mileage on gas did you start seeing an improvement?
Here is my VoltStats MPGcs over the last 1.5 years. I currently have about 5,000 miles on the ICE.
As you can see from the Blue graph, every time I take a trip over 100 miles the average goes up (including my last trip in August). It gradually ticks down every six weeks due to Engine Maintenance Mode. I typically drive with Cruise Control set at 75mph. My current MPGcs is at 38.21mpg

MPGcs.jpg
 

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Gen 1 stats:
VoltStats shows my MPGcs to be hovering around 41mpg lifetime. When I am using gas I rarely if ever go above 70mph and I'm not using LRR tires currently. I do keep them at 40 psi front and rear. Shell Premium gas. 16,369 gas miles.

Gen 2 stats:
VoltStats shows my MPGcs to be hovering around 48.6mpg lifetime. My wife drives the gen 2 and rarely goes above 65mph. She's using the OEM Michelin LRR tires and I keep them at 40 psi front and rear. Shell Regular gas. 16,663 gas miles.
 

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Gen 2 stats:
VoltStats shows my MPGcs to be hovering around 48.6mpg lifetime. My wife drives the gen 2 and rarely goes above 65mph. She's using the OEM Michelin LRR tires and I keep them at 40 psi front and rear. Shell Regular gas. 16,663 gas miles.
I mostly stay under 65 as well (hard to do more on the highways near me), and average very close to 50mpg.
 

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We have a 2016 Volt Premier. Last trip Monday we got 51 mpg on just gas for well over 110 miles on a 168 mile round trip. We keep all 4 factory tires, Michelin Energy Saver AS, at 44 PSI cold tire pressure. Oil was changed and replaced with Mobil One synthetic motor oil, 0w20, as well. Here is our voltstats.net for our Volt. Lifetime MPG's just on gas, 46.61, regular 87 octane 10% ethanol, for 8,771 miles just on the Volt's gas engine.

Your Volt will improve in time for mpgs on the gas engine.

Location: Seaside, OR
Last Updated: 10/17/2017 11:38:09 PM CST
EV Miles: 17888.88 #1954 / 43.8%
Total Miles: 26659.84 #1875 / 46.0%
EV %: 67.1% #2246 / 35.3%
MPG: 141.67 #1811 / 47.9%
MPGe: 74.69 #1433 / 58.8%
MPGCS: 46.61 #218 / 93.8%
Achievements
 

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In order to get a correct mpg, you need to deal in real data. Fill tank, drive in gas mode only, refill tank, devide miles driven by fuel used. Then, in order to compare this data to the other car, you would have had to have done the same procedure with it. Anything else is supposition and conjecture. If you want to improve mpg, you need to reduce mph.
 

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ISo did some of you long term owners notice a gas MPG improvement over time? If so, what mileage on gas did you start seeing an improvement?
It improved instantly for me when I bought the Bolt EV, haha. On my 2011 Volt, the MPG has never really changed. The only way I can see that happening is due to tire wear.
 

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Discussion Starter #18
I appreciate all the responses. Looks like there might be another issue in play and I'll start another thread as it may help others.

Got flashing "service high voltage system" messages and MIL lit. Freaked me out on a car with only 1800 miles on the ODO.

Called OnStar -- codes are P1E00, P1FFD, P1FFF. They said to service it "at your convenience..."

Unfortunately, it's not very convenient because the Volt now won't accept a charge!

I'll follow up on another thread with the results and will (hopefully) report back here if there is a subsequent MPG improvement as result.
 

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I appreciate all the responses. Looks like there might be another issue in play and I'll start another thread as it may help others.

Got flashing "service high voltage system" messages and MIL lit. Freaked me out on a car with only 1800 miles on the ODO.

Called OnStar -- codes are P1E00, P1FFD, P1FFF. They said to service it "at your convenience..."

Unfortunately, it's not very convenient because the Volt now won't accept a charge!

I'll follow up on another thread with the results and will (hopefully) report back here if there is a subsequent MPG improvement as result.
Shouldn't have affected your MPG at all before the DTC was set. For reference, that combination of codes indicates a failed battery pack coolant temperature sensor. According to the service manual, it disables charging as a safety precaution so that the battery doesn't overheat due to the faulty sensor. Hopefully your service trip will be shorter than mine :)
 

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Discussion Starter #20
Shouldn't have affected your MPG at all before the DTC was set. For reference, that combination of codes indicates a failed battery pack coolant temperature sensor. According to the service manual, it disables charging as a safety precaution so that the battery doesn't overheat due to the faulty sensor. Hopefully your service trip will be shorter than mine :)
I agree, but still being hopeful.

Yikes, faulty temp sensor? I had this issue on my Gen 1 and they replaced part of my battery pack--that was around 40K miles. Only got 1800 on the ODO now. I understand Gen 2 battery is easier to fix the temp sensor. Looks like I might be finding out...

What was your experience?
 
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