I am convinced that the KWh/1oo miles info provided on the MyVolt.com site and in the OnStar Monthly Reports is way off for my Volt and I am curious if others are seeing this as well. If this is a consistent issue with most Volts, the problem is in how OnStar determined this figure. If others are OK, the problem might be the data my specific Volt is/has uploaded.

Here are some specifics: (Note: Data reported for MPG on gas is correct, so this issue is on the electric side only. ) MyVolt.com lists my lifetime to be 39 KWh/100 miles. Each of the three reports I have recieved since I picked up my Volt have steadlity increased from 33 in Nov, 38 in Dec and 44 in my Jan report. To get to 39 KWh/100 miles, I would expect my typical AER to be around 26 miles assuming 10 KWh per charge. My Volt's estimated range has never been below 30 (when it is really cold) and is usually between 35 and as high as 48 when it was really warm outside for a couple of weeks. This estimate has proven to be pretty accurate based upon the times I have run it to 0 and automatically switched over to gas. I would expect 48 miles of range to translate into a bit over 20 KWh/100 miles and 30 mile range to translate to under 34.

I have tracked my daily consumption and miles traveled as reported by my car on the center console when I am finished driving for the day and plug in at home. I generally use between 8 and 10 KWh and drive between 24 and 30 miles. Based upon my data gathered over the past month, I expect I should be closer to 32-35 KWh/100 miles and not the 44 reported on my last report.

Is this consistent with what others are seeing for their Volt's or is this just me? If it is just me, does anyone know what could make this happen?

I am convinced that the KWh/1oo miles info provided on the MyVolt.com site and in the OnStar Monthly Reports is way off for my Volt and I am curious if others are seeing this as well. If this is a consistent issue with most Volts, the problem is in how OnStar determined this figure. If others are OK, the problem might be the data my specific Volt is/has uploaded.

Here are some specifics: (Note: Data reported for MPG on gas is correct, so this issue is on the electric side only. ) MyVolt.com lists my lifetime to be 39 KWh/100 miles. Each of the three reports I have recieved since I picked up my Volt have steadlity increased from 33 in Nov, 38 in Dec and 44 in my Jan report. To get to 39 KWh/100 miles, I would expect my typical AER to be around 26 miles assuming 10 KWh per charge. My Volt's estimated range has never been below 30 (when it is really cold) and is usually between 35 and as high as 48 when it was really warm outside for a couple of weeks. This estimate has proven to be pretty accurate based upon the times I have run it to 0 and automatically switched over to gas. I would expect 48 miles of range to translate into a bit over 20 KWh/100 miles and 30 mile range to translate to under 34.

I have tracked my daily consumption and miles traveled as reported by my car on the center console when I am finished driving for the day and plug in at home. I generally use between 8 and 10 KWh and drive between 24 and 30 miles. Based upon my data gathered over the past month, I expect I should be closer to 32-35 KWh/100 miles and not the 44 reported on my last report.

Is this consistent with what others are seeing for their Volt's or is this just me? If it is just me, does anyone know what could make this happen?

I haven't actually compared my report in the car to Onstar's report. The one thought I have, though: There's a ~20-30% loss in charging (takes 12.5-13kWh from the wall to produce the 10.2kWh in the battery.) Could Onstar be adding that back in, to produce wall/utility cost comparable efficiency results?

FWIW the myvolt.com kw-hr/100 miles for my car appears fairly accurate when compared against mileage tracked at voltstats.net and the consumption tracked by mychargepoint.net (I have a 240V Coulomb CT500 EVSE). I'm at ~30.5 kw-hr/100mi from the end of October when I got the EVSE. Myvolt / onstar monthly report reports 30 kw-hr/100mi lifetime, 31 for December, which seems about right. I had better mileage in September/October with the warmer temps before I got the fast charger.

The kw-hr displayed by the car on the center console doesn't account for charging losses. My last drive, car said it took 9.9 kw-hr before it switched to gas, but it took 11.569 to recharge to full on the Coulomb. Losses on 120v are somewhat higher, I've seen it take as much as 13.5 measured with a kill-a-watt when car used 10.3 (including losses from running cooling system due to high temp).

I haven't actually compared my report in the car to Onstar's report. The one thought I have, though: There's a ~20-30% loss in charging (takes 12.5-13kWh from the wall to produce the 10.2kWh in the battery.) Could Onstar be adding that back in, to produce wall/utility cost comparable efficiency results?

That's a good question and on the order of the differance I am seeing. It would be nice to see the actual data that my Volt is uploading to OnStar. Maybe my VA can get that for me?

The kw-hr displayed by the car on the center console doesn't account for charging losses. My last drive, car said it took 9.9 kw-hr before it switched to gas, but it took 11.569 to recharge to full on the Coulomb. Losses on 120v are somewhat higher, I've seen it take as much as 13.5 measured with a kill-a-watt when car used 10.3 (including losses from running cooling system due to high temp).

Insideline had something interesting to say about that today, actually:

http://blogs.insideline.com/roadtests/2012/01/2011-chevrolet-volt-changing-battery-performance-over-time.html#more

Apparently the battery cooling is a substantial and visible factor in charging losses...

Insideline had something interesting to say about that today, actually:

http://blogs.insideline.com/roadtests/2012/01/2011-chevrolet-volt-changing-battery-performance-over-time.html#more

Apparently the battery cooling is a substantial and visible factor in charging losses...

Cool article.. almost deserves its own thread :-)

Good idea about the separate thread. Could be the most interesting tidbit Edmunds has come up with for their Volt test. A lot of what they've written has been borderline idiotic.

I almost started one, but I decided not to initially, and then this discussion on the same topic popped up. If someone wants to make a thread, go ahead. :)

My stats on MyVolt.com are way off... Mine says 15kWh/100 miles? I wish.