• Oct 15, 2009
Chevy Volts on 1,200 mile drive - Click above for high-res image gallery

Yesterday, we had an opportunity to chat with Chevrolet Volt chief engineer Andrew Farah as he rode through the hills of West Virginia during a development drive. On Tuesday, a fleet of eight pre-production (a.k.a. IVER) Volts set out from the company's Milford Proving Ground in Michigan on three day, 1,200 mile jaunt through Ohio, Pennsylvannia, Maryland, West Virginia and back. This event is known in General Motors' engineering process as a "65-Percent Drive" and as it implies it's one of a series of milestones on the road to production.

The 65 complete. Over the next several months, 70, 80, 90 and 100 percent drives will follow on the way to production launch a year from now. Read on to find out what we learned from Farah.




This drive is being used evaluate a variety of aspects of real world performance – especially the charge sustaining mode. Over the course of the drive, at various times, parts of the fleet are being run with a full charge while others are being run with the battery depleted. For example, on day two, only half of the cars were plugged in overnight at the motel, a scenario that is very likely to occur on a road trip with the Volt. According to Farah, regardless of the state of charge, overall vehicle performance was comparable and there was no degradation.



One of the big questions about the Volt's charge sustaining mode has been the behavior of the engine and overall NVH characteristics. Early on, the thought was that during charge sustaining mode, the engine would simply run at a constant speed to maintain the battery level. However, over time the engineering team realized that wasn't necessarily the most efficient way to run the engine. The engine-generator will be feeding power directly to the drive motor on an as-needed basis, with any surplus energy going to the battery.

The generator won't be trying to completely recharge the battery, as that would be less efficient overall than taking electricity off the grid. However, the actual battery state of charge will fluctuate somewhat around the minimum charge level based on high level power demands and charging from the generator and regenerative braking.

The plan now is to run the engine-generator between approximately 1,200 and 4,000 rpm. A map that looks at factors like speed and power load requirements will be used to select the desired engine speed. Because engines typically run more efficiently at higher loads where they can avoid pumping losses, the intent is to keep the engine between 30 and 100 percent load whenever possible. Farah declined to get specific about just what kind of mileage the Volt is currently getting in steady state charge sustaining mode.



Farah did tell us that the final capacity of the fuel tank has not yet been decided upon, but that the prototypes are currently easily exceeding the 300 mile range target on a tank. The cars are not being run to full empty on this trip, but based on the amount of fuel that was put in on the first two fill-ups, 300 miles won't be an issue with gasoline. The Volt, of course, is also a flex-fuel vehicle and some of the cars will be filled with E85 on the final day before returning to Milford.

At this point, the cars are running in near ideal conditions for a battery powered car, not to hot or too cold – both conditions that degrade performance. Farah acknowledges that there are still some "node" inefficiencies in the pre-production vehicles, so in their current form, they aren't quite hitting the 40 mile range target – but they are close. He expects to hit the bogey with the next round of testing.

Another aspect of the Volt's behavior that is being evaluated is its noise, vibration and harshness. As we know, electric vehicles are typically very quiet, and the Volt is in essence an EV. The concern is that when the engine generator starts up, there will be a significant increase in noise. Farah tells us that in general, the Volt will always be running in EV mode at startup and low speeds. Typically, the engine won't come on until the vehicle is motion, when factors like road and wind noise start to overwhelm any sound of the engine. Nonetheless, Farah seems satisfied with the powertrain NVH, although the crew is still working on some road and wind noise issues between 25 and 40 mph.



The silent start likely won't always be the case, however. As we've previously heard from GM's Denise Gray and Bob Kruse, in cold conditions the engine may start up immediately to help support the heating and defrosting needs of the car. This will be especially true if the Volt hasn't been plugged in. No doubt this will be one of the major issues evaluated during cold weather testing over the next several months.

Recently, another team of Volt engineers took the car to Pikes Peak in Colorado for evaluation as it climbed the 14-mile road to the 14,000-foot summit. One of the concerns about the the Voltec powertrain has been that once the battery is depleted, the performance of the car would drop significantly. Because the battery is typically only used down to about 30-35% charge, there is some reserve left over when the engine-generator is running. When at full power beyond the engine-generator's approximately 100 hp output, the battery can be drawn down further.

Eventually, however, the battery will reach a point where it can't provide any more juice. Beyond that, only the engine generator provides power, a condition Farah dubbed the "tipping point." According to GM engineer John Blanchard, "The entire trip was run in charge sustaining (range-extended mode) and system was able to maintain State of Charge during the entire drive." If that is true, it bodes well for any kind of real world usage pattern never hitting that tipping point.

Not having experienced the Volt's charge sustaining mode firsthand, we'll reserve judgment and take Farah at his word – for now. Once Farah and his team return to Michigan late Thursday, they will start diving into all the data and notes to determine what areas still need more work before the 70 Percent Drive. Perhaps with any luck, we'll join the party.


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  • 52 Comments
      • 5 Years Ago

      There is a lot of controversy regarding the state of the Volt.
      I think the Volt will prove to be a niche player in the Green/sustainability game. Though the price is forty thousand dollars for a Volt, the performance will be quite excellent. The only concern I have as a buyer is how am I going to charge the Volt vehicle if I live in the city or if I park car on the street. So, there must be ways to coordinate multi level infrastructure for docking stations for the Volt and other electric range vehicles. I assume that the agenda/policy makers of the twenty first century will invest heavy money into making the infrastructure for EV proto types a reality.

      I mean, Apple was heavily pushed as the MP3 player for the next generation. Even though, most people were still happy with their CD players. And Apple was even heavily pushed onto the public with the iphone device that would integrate MP3/Video/Phone/social networking/mini computer to a more digital world. (Though companies are obliterating Apple's technology)

      There is no reason to think that GM, a global corporation with heavy influence from powerful shareholders, will not approach the same level of change that Apple has done for the PC industry. Apple was bankrupt only a decade ago and look where they are today. It would not be out of the possiblity to see GM assuming a leadership role in electic vehicle production, just like Apple as in the consumer electronics market.
        • 5 Years Ago
        I can see it now, ornery Prius/Insight owners walking the streets at night unplugging Volts just for spite!
      JDM Life
      • 5 Years Ago
      ......this car again?



      Good dammint.....even the LF-A is going to hit production before this....
      • 5 Years Ago
      There should be enough purchases from eco-conspicuous consumers to sustain this car at low volumes, and over time, as the price comes down, sales volumes will increase. As economies of scale lower the price during the next decade, cars with this power-train will sell in large numbers and bridge the gap between our current gas-powered cars to our future all electric models.
      • 5 Years Ago
      I like how they didn't even bother to paint the bumpers. This way when they want to (re)sell them cars as 'new' cars all they will have to change is the bumpers.
        • 5 Years Ago
        you're comment doesn't even make sense. First, they don't sell pre-production vehicles. Second, if they did sell them... how the hell does not painting the bumper now and painting it later make it easier for them to sell? Maybe you're suggesting that if they hadn't painted the bumpers already, they wouldn't have anything to do before selling them and they'd be really bored without that extra bumper painting to do?
        • 5 Years Ago
        No pre-production cars of this level ever have body color painted bumpers. There's no real point to doing it. All they're doing is making sure everything works. It sticks out so much because GM didn't put any camo on them. I'm sure most of the interior isn't grained and they probably don't have airbags either. And not, they cannot legally sell these or use any parts off of them for later builds either. They'll probably end up as crash test vehicles.
      • 5 Years Ago
      Sounds to me that the VOlt's engine will be making 'alot of noise' trying to keep the battery charged and powering the car. I think this will be a big problem. They really needed to put a larger engine/generator in the car. With this smaller power plant, it will be over worked and over revved. Especially when driving in cold winter/hot summer conditions with the generator having to work extra hard keeping the occupants comfortable. Would you want to drive a car that runs at 4K rpm to keep the vehicle moving/heated/cooled? Not something most consumers will want to drive.
        • 5 Years Ago
        RTFA. The GM engineer said that they are designing the ICE to run within a range of RPMs from 1500-4000 based on load. If you put the accelerator to the floor, you typically don't mind hearing from the engine, and it seems that it'll be capable of running in much quieter RPM ranges when there are low power demands.
      • 5 Years Ago
      I do not believe the Volt made the 14 mile climb up PP without hitting the tipping point unless it was in very slow motion!! ROFLMAO!
        • 5 Years Ago
        Hrm, who should I believe... multiple engineers and independent reviewers? Or some loon with a keyboard who thinks that "ROFLMAO" is the pinnacle of english literature?
        • 5 Years Ago
        Why is this hard to believe. Pike's Peak is steep but I doubt you drive the roads at 80 per hour. The energy required to maintain freeway speeds is probably very close to the energy required to climb Pike's Peak at a reasonable rate. If most small ICE powered cars are power limited to around 100 miles per hour and can climb PP why couldn't an electric car that is probably limited to a similar top speed by power do the same?
        • 5 Years Ago
        There are some second-generation Civic Hybrids running around that will not climb a steep hill once the battery assist is gone. And those have a regular gas engine that never stops running when the car is moving.

        So I think the Volt is looking very good in the capability department. They should make a commercial of it climbing Pike's Peak.
        • 5 Years Ago
        WRT the whole pike's peak drive to assess the engine's capability to provide enough power to get up the mountain, it is a silly test.

        Instead...

        Start out in either Golden, Georgetown, or even better - Silverthorne - with a discharged battery and then see how fast you can drive up I-70 to Eisenhower tunnel.
      • 5 Years Ago
      The car for the liberal elite so they can travel what was America to spread their green marxist religion and not feel guilty. Enjoy your appliance.
      • 5 Years Ago
      "Thankfully", there will be a massive golden bowtie on the front of the production model.
      • 5 Years Ago
      I would love this car/project to succeed globally. Wishful thinking?

      http://www.carnorama.com
      • 5 Years Ago
      You could buy a Lexus HS250 with some nice options for this amount of money.

      They're asking you to buy a CHEVY for the price of a LEXUS. Which badge and dealership experience would YOU choose? Hmmm?
        • 5 Years Ago
        The Lexus uses tested technology with Toyota reliability, the Volt when (and IF?) it comes out will use entirely real-world untested technology from General Motors. General Motors, who gave us such "breakthroughs (sarcasm) as the engine in the Vega, the Olds diesels, the Cadillac V-8-6-4....need I go on? You really want to gamble your money (and I remind you, the TAXPAYER'S MONEY) on that?
        • 5 Years Ago
        True intelligence will realize that the Lexus is simply an overpriced Prius and the Volt is an entirely unique and new technology and has some interesting merits despite the high sticker price.

        Of course some fools (who have more money than they need) will buy the Lexus because they like to impress others or actually think that dealer hugs and a few extra gizmos are worth all the extra wasted money.
        • 5 Years Ago
        The Volt will use technology which is in many ways similar to that used for decades in railroad locomotives produced by GM's former EMD company. The difference is miniturization and storage capacity added via battery. Those locomotives are bullet proof and deal with much tougher lifecycle issues than an automobile ever will. Also remember GM had some good real world electric drive experience over a decade ago with the ever in-famous EV1. A decade is a long time to improve on something that had a plug in only range of up to 140 miles way back in 1999.
      • 5 Years Ago
      Let the hate rants begin. I love the fact that GM gets crap for not being like Toyota and having a Prius, so when they try to do something like the Volt they get flamed all over the blog sites. Lets face it, if Toyota, Honda, BMW, or Hyundai made the Volt, every beige loving CamCord driver would be lined up around the block to get one.
        • 5 Years Ago
        And they'd be saying, "Why doesn't GM do something like this? This is why they suck.
      • 5 Years Ago
      Why is it that they still can't build a car that can compete with Prius, instead of building one they come up with this 40k monstrosity that has 40 mile at most battery range.
        • 5 Years Ago
        So, what's the Prius range on battery only?

        Can I drive a Prius back and forth to work (16 miles a day) without putting any gas in it?

        Can I get a Prius without one of the ugliest interiors I've seen in decades?
        • 5 Years Ago
        To repeat what Cmicasa quoted above:

        Henry Ford said, “If I’d have asked my customers what they wanted, they would have told me ‘A faster horse.":
        • 5 Years Ago
        what's the prius electric only range?
        • 5 Years Ago
        http://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain#Series_hybrid

        This technology leapfrogs what the current-gen Prius can do. Get your facts right.
        • 5 Years Ago
        @Aznauto Do you mean the "40k monstrosity that has 40 mile at most battery range" as opposed to the 3 miles the Prius can do on battery power alone? But only if you stay below 30 miles per hour... And as long as the car is warmed up first... And its not too cold outside... And you don't accelerate too quickly... After the 40 miles of pure electric in the Volt are done you end up with the same efficiency as the blessed Prius. Only difference here is that a 40 mile range is statistically sufficient for 80% of your trips. When was the last time any of us drove somewhere within 3 miles at less than 30 mph?

        Then don't forget that the first generation Prius was a lot more expensive than the stripped down version they advertise in the mid 20k range. That estimated $40k comes with the same tax break that the first Priuses got. That means that until GM gets the gen 2 Volt out which they has already said is in the works and is focused on optimizing cost the average Volt and the average Prius will be within $5-7k of each other.

        Any defender of the Prius should do it out of concern for the environment or foriegn oil independence. With these goals in mind you have to recognize that purely electric vehicles are better than the Prius or the Volt. However, the Volt is the only practical way to implement electric cars as a mainstream source of transportation. It removes the chicken and egg paradox of electric car vs the charging infrastructure. You get an electric car for 80% of your driving needs and the ability to utilize the current fuel infrastructure for the rest of your trips.

        Don't get me wrong, the Prius was a great technological leap... 10 years ago. And pure electric cars without an onboard ICE will be the big thing... 5-10 years from now after we have an infrastructure for recharging the cars and battery packs with real world range that aren't $25-$20k. GM has acknowledged that the Volt is a transitionary car. The power train is designed anticipating new technologies in the future and provides way for GM to quickly integrate those new technologies into next gen vehicles as the tech becomes available. The Volt is a car that is designed from the ground up with the future in mind.
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