The EPA list the Volt when in gas engine mode of 38 MPG average. When I look at Volt Stats I noticed that the average MPG in gasoline engine mode is much lower than that. Why such a big difference in real world and EPA?
alfon
Many things influence this. I noticed that when I drive about 80-85 on Interstate, my MPG drops to about 35 mpg. When I drive a more reasonable 70, I get closer to 40 mpg. Seems like I also get mileage at night than day.
Actually I am impressed I that I get 40 mpg. Usually it seems the rating is higher than actual.
Actually I am impressed I that I get 40 mpg. Usually it seems the rating is higher than actual.
While certainly not the voice of authority, I would say that the EPA results are based upon specific testing criteria that doesn't always (read: rarely) apply in the real world. In my experience, the gas engine economy varies heavily on how you use (or abuse) it. I've had highway mileage (interstate) that was around 34mpg. On the other hand, if you consider the mileage range estimates if you run in Mountain Mode frequently, the engine averages only about 21 mpg (full tank estimating a range of 202 miles, assuming a capacity of 9.3 gallons). These numbers are more applicable to my situation since I do not have a consistent way to charge without MM. I wouldn't expect the average user to get these results. These numbers also only reflect the time the gas engine is running and does not include the mileage that I get out of the battery each time I "juice" to 45 to 50% on MM. Overall I get somewhere around 39 to 42mpg if you include the range granted by the battery and the gas engine together. Hopefully this isn't too off target for your question.
It's all about the operating conditions. The EPA tests are specific defined speeds and distances, and thus comparable from car to car. But no one really drives exactly like the EPA - and how your driving differs from the EPA testing will determine how your mileage may vary.
On the highway, it's easy to exceed 40 mpg with the Volt. But like any other car it doesn't like cold much - and because of EMM and ERDTT, a larger percentage of Volt engine time is spent with the engine cold. No car gets good mileage before the engine warms up fully - and both EMM and ERDTT terminate when the engine becomes fully warmed up.
If you look at folks with relatively low %EV - folks who are actually driving on the engine for more than a couple miles at a time on a regular basis, I think you'll find they generally meet or substantially exceed the EPA guidance.
On the highway, it's easy to exceed 40 mpg with the Volt. But like any other car it doesn't like cold much - and because of EMM and ERDTT, a larger percentage of Volt engine time is spent with the engine cold. No car gets good mileage before the engine warms up fully - and both EMM and ERDTT terminate when the engine becomes fully warmed up.
If you look at folks with relatively low %EV - folks who are actually driving on the engine for more than a couple miles at a time on a regular basis, I think you'll find they generally meet or substantially exceed the EPA guidance.
Thanks for the replies. What I gather is that many times when you run out of electricity range the gas engine may only kick in
for a few miles and not have time to heat up to optimum temperature. Its probably like our 2010 Prius, when we drive it after sitting all night the first few miles we are only getting in the 20 mpg range. After the engine warms mpg's go to 40 and 50 mpg's. I am sure
that could be the main reason for Volt Stats.
for a few miles and not have time to heat up to optimum temperature. Its probably like our 2010 Prius, when we drive it after sitting all night the first few miles we are only getting in the 20 mpg range. After the engine warms mpg's go to 40 and 50 mpg's. I am sure
that could be the main reason for Volt Stats.
A lot of times the engine barely warms up because it's on for only a couple of minutes or even just seconds sometimes....
MrEnergyCzar
MrEnergyCzar
While I've not done an extended test (over 20 miles) I've yet to see even 20 mpg out of mine, and that's with new oil, 5w-30 mobil one. There are about 100 gal worth of gas through mine, so it's not break in, and the tests were done at no speed above 45 mph, where I regularly get very close to or exceed 50 mi/charge in warm weather. I can't tell if there's some going into the batteries as well - that would account for it on a ten minute test, I suppose, and obviously, if you're in mountain mode and started below its limit, it's not going to be reported correctly. But 20 - or less - is the best I've seen so far. It's not spewing black smoke, I'm not driving it fast enough to hit the wind resistance "wall" above 50, or anything like, but in most of my use-cases, I simply never would drive it more than 10 or so miles on gasoline, so maybe it just takes a very long time to warm up and get efficient? I tested it today, since I had a long (for me) trip. In 10 miles I used half a gallon. Again. Engine sounds like a swiss sewing machine, there's nothing obvious wrong.
So, Walter, are you saying that to see this kind of mileage, I have to go 100 miles or more? I did get a 2012 Cruze LT up to 36 when I owned it, and drove it harder than I do the Volt (for testing, that is).
So, Walter, are you saying that to see this kind of mileage, I have to go 100 miles or more? I did get a 2012 Cruze LT up to 36 when I owned it, and drove it harder than I do the Volt (for testing, that is).
The EPA doesn't drive my car, I do.
For me, I get significantly less than EPA estimated MPG because my engine only operates under very tough conditions. It barely runs long enough to warm up, only operates under high load conditions, and frequently needs to overcome both aggressive driving style and low temperatures. With that as a backdrop, I'm extremely pleased to be getting "only" 32 MPG for the rare times I'm actually burning gas. EV usage included, I'm sitting at 220 MPG. That's tough to beat with anything other than another Volt.
Under friendlier usage patterns while taking a road trip with cruise control set at 70, the EPA estimate is about 7 short of actual results. Considering that I fully understand WHY I normally get "crappy" mileage from the ICE when burning gasoline, I couldn't be happier with the real world results I get. My other vehicle is having a great day when it get 16 MPG of diesel fuel.
For me, I get significantly less than EPA estimated MPG because my engine only operates under very tough conditions. It barely runs long enough to warm up, only operates under high load conditions, and frequently needs to overcome both aggressive driving style and low temperatures. With that as a backdrop, I'm extremely pleased to be getting "only" 32 MPG for the rare times I'm actually burning gas. EV usage included, I'm sitting at 220 MPG. That's tough to beat with anything other than another Volt.
Under friendlier usage patterns while taking a road trip with cruise control set at 70, the EPA estimate is about 7 short of actual results. Considering that I fully understand WHY I normally get "crappy" mileage from the ICE when burning gasoline, I couldn't be happier with the real world results I get. My other vehicle is having a great day when it get 16 MPG of diesel fuel.
Most of my highway runs are over 40mpg unless i need to run AC or wipers/lights and rain cuts mpg down.
There's two main reasons that I'm aware of for the "real world" Volt engine-only MPG appearing lower than EPA estimates:
1) Since the Volt never needs the engine to turn on as long as it has battery energy left (exception: below freezing temperatures), the Volt has many engine starts that only go for a mile or two. Because of this, a larger percentage of engine run time is while the engine is cold, making the MPG numbers look statistically worse. Also as others noted, you can view histograms on VoltStats.net and you'll see a large number of gas trips of very short duration, validating what I've stated here.
2) Many people not fitting into #1 may travel less than 20-30 miles with the engine on, and at speeds lower than 50mph (read: DCFusor above). When this is the case, some of the electricity is going from the engine's generator back into the batteries (this is in part why the engine will cycle on and off at these lower speeds). Unless you reach your destination at just the right time, some energy will be stored in the battery from gasoline, which will also make the engine MPG numbers look artificially low. As trip distance increases, this energy stored in the battery is a lower and lower percentage of total energy used, so longer trips will not bias the MPG numbers downward in any meaningful way.
As others noted, on long trips the Volt performs well from a fuel efficiency standpoint... long trips eliminate the chances of the two "biasing" cases above from occurring.
1) Since the Volt never needs the engine to turn on as long as it has battery energy left (exception: below freezing temperatures), the Volt has many engine starts that only go for a mile or two. Because of this, a larger percentage of engine run time is while the engine is cold, making the MPG numbers look statistically worse. Also as others noted, you can view histograms on VoltStats.net and you'll see a large number of gas trips of very short duration, validating what I've stated here.
2) Many people not fitting into #1 may travel less than 20-30 miles with the engine on, and at speeds lower than 50mph (read: DCFusor above). When this is the case, some of the electricity is going from the engine's generator back into the batteries (this is in part why the engine will cycle on and off at these lower speeds). Unless you reach your destination at just the right time, some energy will be stored in the battery from gasoline, which will also make the engine MPG numbers look artificially low. As trip distance increases, this energy stored in the battery is a lower and lower percentage of total energy used, so longer trips will not bias the MPG numbers downward in any meaningful way.
As others noted, on long trips the Volt performs well from a fuel efficiency standpoint... long trips eliminate the chances of the two "biasing" cases above from occurring.
Here are my last 11 months of month-by-month Charge Sustaining (hybrid mode) mpgs from Voltstats.net (when I first joined) while driving overall at about 20-30% on gasoline (typically 20-30 miles on the gas engine) on a commute that is typically around 90-120 miles per day:
MPGCS
47.01
48.46
47.63
47.24
45.45
48.81
50.56
46.02
42.70
46.49
According to myvolt.com, my average CS mpg during the past year is 46.6 mpg.
I got this driving about 85% on the highway at 55-60 mph and the rest on city streets at posted speed limits. My gas miles are mostly on the way home where the house is 500-600 ft. above sea level. Some days the engine starts when I'm near sea level and some days I'm up in the hills between 500-1000 ft. on the way home. I think it's realistic for a long-term average for someone driving conservatively in the Volt on gas who is aware about how to drive efficiently. I do it routinely with very little effort in the SF Bay Area with temperatures between 40-85F with minimal use of climate controls.
My voltstats URL is: http://www.voltstats.net/Stats/Details/2456
MPGCS
47.01
48.46
47.63
47.24
45.45
48.81
50.56
46.02
42.70
46.49
According to myvolt.com, my average CS mpg during the past year is 46.6 mpg.
I got this driving about 85% on the highway at 55-60 mph and the rest on city streets at posted speed limits. My gas miles are mostly on the way home where the house is 500-600 ft. above sea level. Some days the engine starts when I'm near sea level and some days I'm up in the hills between 500-1000 ft. on the way home. I think it's realistic for a long-term average for someone driving conservatively in the Volt on gas who is aware about how to drive efficiently. I do it routinely with very little effort in the SF Bay Area with temperatures between 40-85F with minimal use of climate controls.
My voltstats URL is: http://www.voltstats.net/Stats/Details/2456
Temp, Terrain, luck....etc.
We've now run 222 gallons though our Volt in 11 months of ownership. I do all of our highway driving while my wife sleeps (except for the times we go to new places) and drive at, or slightly below, the posted speed limit.
Our summer vacation accounted for 144 gallons of that covering 6,000 miles over mostly mountains and a few plains.
Our lifetime MPGcs average was 37.60 before the long trip with about 50 gallons through the engine at that point. It is now at 38.25 - which is actually a drop from it's all-time high because of another trip to the border (casino) since our vacation The drive across the flatter legs of the long trip (e.g the panhandle of Texas - plains) yielded up to 45 MPG with no load - looking at the trip segments on MyVolt.com.
We do quite a few 300-500-mile trips, both to Houston and to the Mexican border. Those are typically right on the mark, averaging 38.
All of these numbers are excluding whatever EV driving we do - just actual miles racked on on gas and not combined with EV miles.
One thing I've begun doing to maximize my MPGcs numbers is to get up to highway speeds on battery before engaging a cold engine when I know that the trip will involve gas usage. Once engaged, I don't switch back to battery once the engine warms up. The computer handles small town slow downs and red lights and stop signs just fine without my help.
Now those .1-3 miles at the very end of a totally EV run are the killers on your stats!!!
We've now run 222 gallons though our Volt in 11 months of ownership. I do all of our highway driving while my wife sleeps (except for the times we go to new places) and drive at, or slightly below, the posted speed limit.
Our summer vacation accounted for 144 gallons of that covering 6,000 miles over mostly mountains and a few plains.
Our lifetime MPGcs average was 37.60 before the long trip with about 50 gallons through the engine at that point. It is now at 38.25 - which is actually a drop from it's all-time high because of another trip to the border (casino) since our vacation The drive across the flatter legs of the long trip (e.g the panhandle of Texas - plains) yielded up to 45 MPG with no load - looking at the trip segments on MyVolt.com.
We do quite a few 300-500-mile trips, both to Houston and to the Mexican border. Those are typically right on the mark, averaging 38.
All of these numbers are excluding whatever EV driving we do - just actual miles racked on on gas and not combined with EV miles.
One thing I've begun doing to maximize my MPGcs numbers is to get up to highway speeds on battery before engaging a cold engine when I know that the trip will involve gas usage. Once engaged, I don't switch back to battery once the engine warms up. The computer handles small town slow downs and red lights and stop signs just fine without my help.
Now those .1-3 miles at the very end of a totally EV run are the killers on your stats!!!
Volt Stats shows the fleet average at 35.71, which is 6% below the EPA 38. This is pretty typical, and maybe slightly better than most cars MPG compared to EPA estimates. Most drivers, regardless of the make and model do not achieve EPA estimates, this is why EPA has a disclaimer (actual results may vary). The EPA estimate is helpful in comparing across vehicles.
As for my personal experience, most of my ICE driving is Phoenix to LA and back at 70 - 80 mph. At these speads I get 37 - 40 MPG depending upon wind.
As for my personal experience, most of my ICE driving is Phoenix to LA and back at 70 - 80 mph. At these speads I get 37 - 40 MPG depending upon wind.
On my long distance cross country drive (in Canada) where I did roughly 3000 miles, I got about 40 mpg on the entire trip. What really surprised me was that hilly terrain vs plains didn't seem to make a difference to the MPG compared to a normal car. I suspect the battery acting like a buffer was the reason for that. (Includes some charging at motels, also had a 120v plug where I stayed.) So I can definitely beat EPA. We also have extremely cold winters up here which includes short trips in which case the MPGcs drops into some very horrific numbers. No surprise thou, almost any car performs horrifically in our winters. I remember the Corolla I used before went through 2x more gas in the Winter!
After I reached 1,000 miles of the ICE running, my Volt seemed to gain MPGs.
I just went to Vegas a couple weeks ago and when going over mountains and pushing the Volt at 65-70 MPH up the mountains, and 70-75 MPH once over the mountains, I got 42 MPG on the ICE. That's for around 560 miles on the ICE. It wasn't a flat run, and the up hills took more away than the down hills gave back on mileage.
When I go on basically flat routes - I'm now getting around 45+ MPGs at 65-70 MPH.
My overall MPG for the ICE after 2,000 miles on the ICE is 35.63, the first 1,000 miles really dragged down the MPG. I driven about 81% on battery, and those short .1 to .3 gallons at a time kill the MPG's also, especially since those are usually miles driven in town, and the engine really doesn't warm up well enough by then.
I just went to Vegas a couple weeks ago and when going over mountains and pushing the Volt at 65-70 MPH up the mountains, and 70-75 MPH once over the mountains, I got 42 MPG on the ICE. That's for around 560 miles on the ICE. It wasn't a flat run, and the up hills took more away than the down hills gave back on mileage.
When I go on basically flat routes - I'm now getting around 45+ MPGs at 65-70 MPH.
My overall MPG for the ICE after 2,000 miles on the ICE is 35.63, the first 1,000 miles really dragged down the MPG. I driven about 81% on battery, and those short .1 to .3 gallons at a time kill the MPG's also, especially since those are usually miles driven in town, and the engine really doesn't warm up well enough by then.
Important Factor: Quoting from the voltstats FAQ:
DEPRECATED: Why do the MPGcs numbers look wrong/weird? Short answer: I don't know.
If one zeros the odometer upon filling the tank, then compares the mpg on the odometer display with the miles/gallon obtained after the next full refill, the numbers match extremely well. Dividing the gas miles by the gas gallons on the energy use display shows good agreement too. However, the [CS] mpg reported by voltstats from info provided by ONSTAR is up to 10% low when using a reasonable amount of gasoline in a reporting period.
Still, given that, the low reported [CS] figures are most often in Volts with a high percentage of EV miles. Cold starts, engine cycling, running in the high-rpm condition, all suck gas relatively speaking.
The engine runs most efficiently at steady speeds on flat ground, fast enough to avoid the on/off cycling, yet slow enough to avoid excessive aero drag. Hills steep enough to kick the engine into high rpm, cost mpgs. Acceleration can also do this to the engine.
My recent results from 853 miles in one day with:
1) A single full charge at home.
2) EV at slow speeds.
3) EV for acceleration from on ramps and toll booths to full cruise speed, then engaging cruise control, followed by "hold" mode.
4) Aim for cruise at 65 -68 mph.
Result = 44.2 mpg
DEPRECATED: Why do the MPGcs numbers look wrong/weird? Short answer: I don't know.
If one zeros the odometer upon filling the tank, then compares the mpg on the odometer display with the miles/gallon obtained after the next full refill, the numbers match extremely well. Dividing the gas miles by the gas gallons on the energy use display shows good agreement too. However, the [CS] mpg reported by voltstats from info provided by ONSTAR is up to 10% low when using a reasonable amount of gasoline in a reporting period.
Still, given that, the low reported [CS] figures are most often in Volts with a high percentage of EV miles. Cold starts, engine cycling, running in the high-rpm condition, all suck gas relatively speaking.
The engine runs most efficiently at steady speeds on flat ground, fast enough to avoid the on/off cycling, yet slow enough to avoid excessive aero drag. Hills steep enough to kick the engine into high rpm, cost mpgs. Acceleration can also do this to the engine.
My recent results from 853 miles in one day with:
1) A single full charge at home.
2) EV at slow speeds.
3) EV for acceleration from on ramps and toll booths to full cruise speed, then engaging cruise control, followed by "hold" mode.
4) Aim for cruise at 65 -68 mph.
Result = 44.2 mpg
My lifetime CS MPG on Volt Stats is 37mpg. That is 1500 CS miles. I agree with the low mpg with EMM and coming on due to cold and engine coming on for the last mile of a trip. I've seen lots of that in my 10,000+ EV miles. But on a trip with longer use of the ICE it is easy to get 40 and have even seen 42. I'm very pleased with mine. 300 Mpg combined at 12k miles
My opinion is that the more the volt operates in EV mode with only occasional ICE use, it will bring down the average CS mpg.
PS
I tend to drive more aggressive and faster when in ICE mode, so my 37 average CS is very pleasing.
My opinion is that the more the volt operates in EV mode with only occasional ICE use, it will bring down the average CS mpg.
PS
I tend to drive more aggressive and faster when in ICE mode, so my 37 average CS is very pleasing.
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