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Discussion Starter · #1 ·
The numbers in the attached photo of my 2012 energy usage screen speak for themselves.

However, additional details may be of interest to some. This was a one day round trip without recharge.

There were periods of rain at both the start and end of the day. Temperature at the start of the trip was 74F and at time of arrival it was 91F. Temperature at start of the return after a five hour layover was 98F. Except for a quick cool down at the start of the return, climate settings were 74F, ECO and middle fan speed. Heat came on at the start of the trip to dehumidify the interior. Mountain mode was used except for the last ~17 miles. The ICE came back on less than one mile from home. D was used throughout. Except when roads were wet, cruise control was generally on and set to the lower of 60 or the speed limit. (Speed limits ranged from 35 to 65.) Except to merge or pass, sprints were avoided and speed was held to 60 or below. Starting tire pressure was 40 psi. Gas was 93 octane.

Factors I believe contributed to the higher-than-I-expected CS MPG are:
---use of slightly higher than recommended tire pressure
---use of 93 octane gas
---use of D to facilitate coasting rather than L which facilitates regeneration
---use of cruise control to avoid frequent small speed changes
---avoiding sprints and high speeds
---use of mountain mode to provide sufficient charge to assist the ICE and perhaps facilitate longer shutdowns
---use of ECO and middle fan speed

KNS
 

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Your actual ICE mileage is very similar to what I was experiencing when I was unable to charge (~ 45 MPG). Basically, when the Volt is driven like a Prius (i.e., avoiding short cycling of a cold ICE), its fuel economy matches the Prius's closely.
 

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GM is to be commended for posting accurate, conservative energy consumption figures. Many owners easily exceed the specs, adding to the already high owner satisfaction numbers. (Unlike certain other brands......)
 

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GM is to be commended for posting accurate, conservative energy consumption figures. Many owners easily exceed the specs, adding to the already high owner satisfaction numbers. (Unlike certain other brands......)
Or certain other GM vehicles. ;) Aerodynamic and small-engined means owners can more easily beat EPA ( although Voltstats actually puts the average below EPA). This is because for many owners highway driving doesn't involve the kind of speed variation and acceleration frequency found on the tests, but typically involves higher average speeds. Aerodynamics reduce the impact of speed, steady speed reduces the impact on the engine. What will hurt the Volt CS figures is that in cold temperatures AER is lower, which then puts more miles in CS mode when CS fuel ecinomy is worse.
 

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Factors I believe contributed to the higher-than-I-expected CS MPG are:
---use of slightly higher than recommended tire pressure
---use of 93 octane gas
---use of D to facilitate coasting rather than L which facilitates regeneration
---use of cruise control to avoid frequent small speed changes
---avoiding sprints and high speeds
---use of mountain mode to provide sufficient charge to assist the ICE and perhaps facilitate longer shutdowns
---use of ECO and middle fan speed
Excellent MPG! And good tips. The jury is still out on D vs L driving. On one side, coasting in D avoids over-braking, but on the other side L encourages deceleration that it guaranteed to be all regenerative. My personal experience seems that with a smooth left foor L is slightly better.

For those of us that have a 2013, using hold mode is a great way to save the battery energy for driving in the city, while running in the efficient power-split mode while on the highway.
 

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I've been reading old threads to optimize our trip driving this summer. One notable difference for us is that we have to go through mountain passes, some of them with a 2000-4000ft elevation gain. It sounds like we should we start off with a full charge and switch mountain mode with at least 15 EV miles remaining. But that may not always be possible. What is the best procedure if we have to start off with no charge due to a lack of charging options at a motel? I am also curious, what is the longest trip folks have taken with their Volt?
 

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Your actual ICE mileage is very similar to what I was experiencing when I was unable to charge (~ 45 MPG). Basically, when the Volt is driven like a Prius (i.e., avoiding short cycling of a cold ICE), its fuel economy matches the Prius's closely.
I had a 2009 Prius and usually hit 46MPG out of it. In the Volt in CS mode, I'm usually hitting 37 driving in the same conditions.
 

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My mileage is all over the map. Interstate, no wind on a flat road, 35-37 mpg. Mountain interstate, no wind, same day return, 43-47 mpg. Same speed, 70 in CC and L. Big difference is that on a dlat road there is never any indication of battery charging through gravity regeneration whereas on the mountain trips, there is a continuous charge, recharge going on. Regenration is 65% efficient, gas generation is 25%. Is that meaningful?
Whwn I get 35 mpg on the interstate, I get annoyed with such a great car, and switch ro "pulse glode" in MM and get it up to at least 42-44 mpg. 20 miles at 20-23 mpg in MM with the ICE on and 20-22 miles on the generated electricity.
 

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I had a 2009 Prius and usually hit 46MPG out of it. In the Volt in CS mode, I'm usually hitting 37 driving in the same conditions.
In the summer, our 2006 Prius would hit 51-55 mpg on a trip without any real effort. But for the bulk of our driving which is on local, rural, hilly roads it was more like 45mpg. The Volt is doing the same now with no ICE intervention.
 

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Factors I believe contributed to the higher-than-I-expected CS MPG are:
---use of slightly higher than recommended tire pressure
---use of 93 octane gas
---use of D to facilitate coasting rather than L which facilitates regeneration
---use of cruise control to avoid frequent small speed changes
---avoiding sprints and high speeds
---use of mountain mode to provide sufficient charge to assist the ICE and perhaps facilitate longer shutdowns
---use of ECO and middle fan speed

KNS,

You used MM on this run ?? If you did ... how/when .. did you just keep in MM until the last few miles ?? I do almost everything you listed, except using MM. 49 MPG is great for an extended run and I would really be interested in the MM usage.
thanks
 

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QUOTE: Whwn I get 35 mpg on the interstate, I get annoyed with such a great car, and switch ro "pulse glode" in MM and get it up to at least 42-44 mpg. 20 miles at 20-23 mpg in MM with the ICE on and 20-22 miles on the generated electricity.[/QUOTE]

I have tried MM on short bursts. My daily commute is 2 sections of highway driving , about 8 miles each. Using MM I did not notice any increase in MPG for these short sections. Do you feel you are getting an increase from around 35 mpg to 42-44 mpg just from using MM (creating the extra EV miles with less ICE miles) ?? I may have to try this on a longer run. Thanks
 

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Discussion Starter · #14 · (Edited)
KNS,

You used MM on this run ?? If you did ... how/when .. did you just keep in MM until the last few miles ?? I do almost everything you listed, except using MM. 49 MPG is great for an extended run and I would really be interested in the MM usage.
thanks
Yes. I turned it on whenever I restarted the car. I use MM (2012s don't have hold mode) whenever there will be significant distance on hilly and/or local roads at the end of a lengthy road trip. I turn it off at a distance estimated to arrive with a depleted battery. Sometimes I end up with one or two miles of AER remaining and sometimes the ICE will frustratingly turn on just a mile or two from home or other destination.

QUOTE: Whwn I get 35 mpg on the interstate, I get annoyed with such a great car, and switch ro "pulse glode" in MM and get it up to at least 42-44 mpg. 20 miles at 20-23 mpg in MM with the ICE on and 20-22 miles on the generated electricity.
I don't use MM to add charge to the battery as that forces the ICE in my 2012MY to run harder and, I suspect, less efficiently. This has been debated at length in other threads. It is my intent to answer your question and not to reopen that debate in this thread.

KNS
 

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After trying it both ways I have settled for MM on trips, especially if traveling in a new area. On one trip to Portland I did not use MM and the genset really had to work hard and hot to deal with the long climb to the west when we went to visit the Pittock Mansion. We were running at Normal and there was no battery reserve. When we pulled into the parking lot there you could smell that it got very hot. Since then we have taken trips with the car in MM and not had a repeat.
 

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As I understand it, driving in MM doesn't allow the engine to lock up to the wheels. Generally at high speed, you don't want MM since the engine is powering the genset only. Given how slow the OP was going (never over 60) I'm not sure that the engine would lockup anyway so it may not have mattered. Out in the west where speed limits are 75-85, you want to use normal or hold and allow the engine to help push you along while it also charges the battery. I also believe it's been demonstrated that the ICE is most efficient in the lower RPM range than the higher RPM range MM requires.

As for L vs. D, I hold the belief that D is better for highway, especially where coasting is used (downhills, slowing for lower speed limits, etc). L scrubs off too much momentum with a relatively inefficient regen (75% max - 65% typical). D allow more the momentum to carry and N would best. Said another way, at highway speeds potential energy > regen energy so cost as far as you can, when you can. Don't trade it for regen energy unless you need to come to a stop or slow dramatically since regen is less efficient than coasting.
 

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I did 2000 miles last week, with only the opportunity to recharge two nights.

Overall interstate travel at 70mph cruise control netted 38mpg (gas only travel, trip meter reset each time after refueling).

This was using 10% ethanol Top-Tier premium fuels, 38psi tires, 5% or less climate power and average 50F ambient temps.

Not quite as good as my 2002 Honda Insight would have gotten (~65mpg), but I sure was more comfortable in my leather seats!
 
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