GM-VOLT : Chevy Volt Electric Car Site

I spent the better part of a warm October day driving a Chevrolet Volt throughout northeast Michigan. This was the culmination of years of discussion, research, writing and dreaming, finally coming true.  I alternated taking the wheel with another journalist and we were accompanied by a GM spokesperson who rode in the back seat.

We took the car through city streets, rural roads, and highways. We ran into stop signs, traffic lights, construction zones and highway entrances and exits. It was an extensive driving experience the likes of which I had never had before with the car which was a fully-refined salable build.

Our day began with a fully charged battery indicating 40 miles of available range. That number is determined based on the behavior of the previous drive, and nowhere was displayed the percent battery range remaining, just the estimated range which gradually moves towards zero as you go.

The first leg of our journey included some spirited freeway romps over 85 mph at times. We were able to travel 36.9 miles before the range extender went on. We continued for another 16.4 miles and arriving after 53.3 miles of driving our total fuel efficiency to that point was 98 mpg.

At our first destination, the DHAM assembly plant, we plugged our car into a cool solar panel charging station (shown above) and about two hours later returned to the car which by then had accrued 24 miles of EV range. After driving off again the range extender went back on that time after exactly 24 miles. We then covered another 30.9 miles to our second destination for a total of 54.9 miles. The fuel economy of that leg measured 66.6 mpg.

Our next to final leg back to the hotel was done only in extended-range mode, at 50 to 60 mph, over flat roads with mild hills. My co-pilot drove the car during that stretch with no particular attention or effort to achieving good fuel economy, and included spirited acceleration and hard stops. We covered 37.4 miles and returned a fuel economy of 37.1 mpg.

I took back the wheel for the last 10 miles and made a particular effort to hypermile the car. I managed to achieve 51.9 MPG over those 10.1 miles.

In the end we traveled 155.7 miles, 60.9 on electricity and used 2.55 gallons of gas. Total fuel economy for this trip thus was 61.1 mpg.

Overall the car was very solid yet seemed light and firmly hugged the road. It handled rough turns like it was painted to the road.  Inside it was bright, cheerful highly technical and spacious.

It was fast and could surge onto the highway and could briskly pass other cars without any discernible strain. I measured 60 to 80 mph time on the highway at 7.8 seconds.  It was a very compelling and confident vehicle.

One could never detect when the car switched from EV to charge sustaining mode. Stepping hard on the accelerator once in CS mode usually produced a noticeable engine noise which seemed faint and muted and followed the expected demand with a slight delay. There was the occasional unexpected rev here and there, but it never created any issues.

Of particular note, no change in sound or behavior could be detected when passing 70 mph in charge-sustaining mode, the controversial state where the ICE always participates in turning the driveshaft.  I repeated this trial numerous times to be sure.

The sound system boomed thr0ugh six speakers, and the HVAC, seat comfort and graphic interfaces were excellent.  Those vivid LCD screens are just awesome.

Overall it was a really outstanding experience that I will always remember. The car is an awesome unlimited daily driver that was highly potent and flexible. With care, more than 50 miles of range and 50 miles per gallon in CS mode could be obtained. With no particular effort or attention to driving efficiently, expect EV ranges and CS MPGs in the high 30s.

For another perspective, you can actually read the review of the reporter who accompanied me on this journey, Seth Fletcher of Popular Science: Never Mind the Naysayers: The Chevy Volt is Excellent

I just returned from Detroit, having  had my first chance ever to take the Volt on the open road for two days of extensive driving.  On the first day, just after touching down, I got to drive a production Chevrolet Volt from the Detroit airport out to Rochester Michigan to the hotel journalists are staying for the Volt launch drive event.  I was on the first wave of journalists with about a dozen others.  There will be six waves in all each with about 20 reporters.  Expect a persistent stream of Volt news over the next week or so.  This event is considered the Chevrolet Volt media launch.


GM had nine final production Volts waiting for us to drive, which we did in pairs of two journalists along with one member of the Volt staff. It was set up as a contest to see who could get the most EV range.  It will continue through the waves.


The distance of the drive was 45.9 miles, and I personally took the car for the first 20 with another reporter driving it the second half of the way. We began with a full battery.


This was the first time I was fully allowed to drive and operate the Volt extensively on public roads. For my part I chose to be careful with the pedal and brakes and to indulge in the pleasures of efficiency.


I found the car to be bright, technical and cheerful as always. The leather seats were comfortable and sturdy and the car was adequately spacious inside though not overly roomy. It was the first time I had seen a final-textured interior surface and found it was well done and gave forth a refined appeal.


On this first journey, I intentionally didn’t gun the car, I accelerated modestly, coasted once in a while, and often kicked into low gear to utilize motor braking. The car handled and glided smoothly, swiftly and silently with crisp, immediate and perky torque and a highly responsive throttle.  It steered like it was floating on air.


When I started out the battery indicator showed 39 miles of range remained. The surprisingly warm temperature outside ranged from 78 to 83 degrees and so I had to use the air conditioning. I kept it at 76 degrees F and used the ECO mode HVAC setting at which the car was quite comfortable. I turned off the daytime running lights and didn’t use the radio.


Within a few miles of driving my remaining range had actually climbed to 41. The roads were mostly flat and I drove at around 45 MPH, with minimal traffic and few stops.


After covering 19.2 miles the meter indicated I still had 31 miles of range remaining. Had I continued for the whole trip at that style of driving I would have easily passed 50 miles of range. Volt director  Tony Posawatz in the car with me said I was “on track for more than 55 miles” of range.  Tony said EV ranges beyond that (though he wouldn’t be specific) had been achieved by several engineers using captured test fleet vehicles.


The second driver, however was considerably more lead- footed and less careful about braking. By the time we arrived at our destination we had traversed 45.9 miles and the meter said we still had 3 miles left, for an effective 49 miles of EV range with our mixed driving styles.  We came in tied for 3rd place in the field of the nine pairs of journalists.  The winner of our wave arrived with 8 miles EV range remaining on his meter.


This real world test indicated there was little doubt one could easily regularly achieve 50 miles or more of electric range with little effort in an extremely efficient, super technological and fun-to-drive car.  Achieving 40 miles of range will likely be the norm.


Soon I will share with you my second day if driving in which I covered over 150 miles on Michigan roads on both EV and extended range mode, and even hypermiled a bit

A significant focal point of the Chevrolet Volt launch debriefing that I attended focused on detailing the inner workings of the car’s electric drive unit. This has been dispersed across the Internet often inaccurately and to much controversy that’s rather unwarranted.

I was one of a handful of journalists that attended a presentation by Larry Nitz, GM’s executive director of EVs and hybrids, in which he fully explained the way the system works.

The system was first designed in mid-2007 at which point GM decided to build what up to then was only a concept Chevy Volt. The patent was applied for around that time, and only two weeks ago the company was advised the patent was awarded.

The key components are the 111 kw electric motor, the 55 kw electric motor/generator, and the 62 kw 1.4 L gasoline engine.

The core element is the large electric motor which always turns the driveshaft. The car is always electrically driven. The motor turns the sun gear of a planetary gearset which itself is then connected to the driveshaft through two sets of gears set at a 7 to 1 combined gear reduction ratio. In this state of driving the generator is used to only recapture kinetic energy during motor braking and coasting which is then fed back into the battery. It is grounded to the crankcase by one of three clutches.

The next drive state occurs when the car is still in EV mode, but reaches around 70 mph. At that point the 111 kw electric motor begins to spins too rapidly and loses efficiency, around 6500 rpm. To improve efficiency the system kicks in the smaller 55 kw electric motor to operate in parallel. GM thought a lot about this element and considered instead adding a second gear, but figured they could simply use the generator because at these speeds, “it’s not doing anything, ” said Nitz. “It’s just along for the ride.”

It does so by releasing a second clutch, disengaging the ring of the planetary gearset from its formerly fixed position against the case, which then causes coupling of the generator into the ring gear of the planetary. The parallel input from the smaller motor then allows the RPMs of the larger motor to be reduced, improving the overall efficiency of the system. By allowing the second motor to participate, engineers gained an additional 1 to 2 miles of electric range.

The third state of the system occurs when the battery state of charge drops to a 20 to 25% state of charge, and extended range or charge-sustaining operation commences. There is still a buffer in the battery used to handle the dynamic responses of the vehicle in this mode.

At low speeds, the gas engine comes on board and spins the generator motor simply to produce electricity sufficient to supplement the battery and supply the electric motor. The engine is locked to the generator through a third clutch, and the ring gear stays grounded to the crankcase. GM calls this a weak one motor series that is battery dominant with the engine in the background picking up the average amount of energy the vehicle needs.

The fourth and controversial state commences when the vehicle reaches speeds of 70 mph while in extended range mode.

As in EV mode the ring gear is decoupled from the case by the clutch and the smaller electric motor is once again allowed to operate in parallel with the large motor, increasing the system’s efficiency. The difference here is that the smaller motor is still being turned by the engine and not electricity. Thus the engine becomes coupled with both electric motors and all three work together to turn the driveshaft. Thus the gas engine participates in turning the wheels mechanically although indirectly. The generator is decoupled from the ring gear again when speeds drop back below 70 mph.

Thus although the engine generator can participate in mechanically driving the wheels it never does so directly or in isolation, at all points in time the large electric motor is the main driver of the wheels.

By adding this element, engineers were able to improve fuel efficiency by 10 to 15%.

There has been considerable blogospheric controversy over this as this appears to contradict GM’s previous statements that the engine never drives the wheels. Nitz said GM had to be coy about this element due to intellectual property reasons, and now that the patent has been awarded can finally be more transparent.  He still says there is no solitary direct mechanical drive because to do so would require a clutch to the sun gear decoupling the 111 kw electric motor, something that doesn’t exist and doesn’t happen.

Does this element play a major role? It depends how often you drive over 70 mph and extended range mode.

Next question. How important is it to you?

See a video of Mr. Nitz’ whole presentation here.

The Chevrolet Volt’s technical details are now being laid bare for all the world to see. Motor Trend magazine was the first to get a full debriefing on how the Volt’s powertrain functions and according to GM engineers I have just spoken with, have done an excellent job explaining this.

As you are reading this article I am spending a full day driving the Volt more than 100 miles throughout Detroit in both EV and extended range mode and attending technical briefings on the inner working of the car. More on this soon.

Frank Markus of Motor Trend took the car for an extended test drive and found it lived up well to GM’s promises. He also explains the inner workings of the Volt’s transmission for the first time. The previously reported patent application found by our own reader Cab Driver was confirmed as accurate.

Here’s how it works.

The drivetrain has a bit in common with the Prius and Ford hybrids. It consist of a single planetary gearset, two electric motors, and one gas engine. Motor Trend thinks the design is superior and more efficient than Toyota’s, and according to GM engineers with whom I spoke, is on the verge of patented.

There is a large central sun gear turned by the 149 horsepower electric motor at all times. Around it is a planetary carrier which turns the wheels. When the car is in charge depleting mode, an outer ring is locked to the case. The engine and generator are disengaged.

When the car reaches 70 mph the main motor spins too fast to be maximally efficient, and a clutch disengages the ring from the case. This allows the second electric motor to participate and both motors act in parallel to reach speeds of 101 mph with adequate power.

In charge sustaining mode, the gas engine goes on and clutches to the generator causing it to produce electricity to continue powering the main motor.

However of particular interest, when going above 70 mph in charge sustaining mode, and the generator gets coupled to the drivetrain, the gas engine participates in the motive force. GM says the engine never drives the wheels all by itself, but will participate in this particular situation in the name of efficiency, which is improved by 10 to 15 percent.

Markus liked driving the car and he noted he was surprised about the direct mechnical connection.

Motor Trend found 0 to 60 in 8.8 seconds in EV mode and 8.7 seconds in extended range mode. This difference was verified to me by engineers. Noting it to be “no sports car” the Volt still blows the Prius away (9.8 seconds 0 to 60).

Though not specifically tesing it, Markus said drivers should expect fuel effieicny when running on gas from high 30s to low 40s.

He also noted the Volt will flash a dash message “low propulsion power” when going up steep grades in extended range mode and will drop to 40 MPH. This will not happen if mountain mode is engaged ahead of time, which will leave extra energy in the battery, causing the engine to go on sooner.

They found it quiet as well as quick and nippy in traffic.

The brakes were noted to be suprtior to the Prius, and do an excellent job mating and feathering initial regenerative motor braking and eventual disc caliper braking.

Motor Trend also was abe to map the behavior of the Volt’s generator and found it generally followed power demand in the way a customer would expect.

Motor Trends bottom line: If the gas/electric and plug-in sport sedans (Fisker, Tesla) and supercars (Jag, Lotus, Porsche, Ferrari) are as well-engineered as this subcompact, enthusiasts need not fear the 60-mpg future.

Source (Motor Trend) and (Motor Trend)

The extensive road-test journalist reviews of the Chevrolet Volt have begun to pour in.

In this case Popular Mechanics took home an unsupervised Chevrolet Volt to test drive for 3 days and 900 miles, and has become the first publication to determine the Volt’s fuel efficiency when in extended range mode.

GM has held to their promise it wouldn’t be be them to who told the world these numbers.

First some new official facts: the Volt’s size is a 105.7 inch wheel base and 177 inch exterior length and it’s weight is 3790 pounds.

The PM driver found the car library quiet inside, and could get it to accelerate from 0 to 60 in the as-promised 8.82 seconds. Top speed was electronically limited to 101 mph at which they found it “tracks like it’s made for the Autobahn.”

The car braked from 60 to 0 in a “quite good” 118.97 feet, surprising for its newly exposed portly weight. They noticed though it had an odd quirk of stopping with more force as the car slowed.
They found the ride comfortable and refined and noticed the tuned power steering lightened considerably as the car slowed.

It was noted the generator went on without being recognized but at times a revving could be heard, that like a CVT did not seem mated to the driving situation.

The reviewer could test mountain mode in the places he drove, but could get a quote from GMs top EV engineer. “In the mountain mode,” said Larry Nitz. “the Volt zips right up Loveland Pass in Colorado at over 70 mph.”

It was perceived that some interior plastic seemed a little less luxurious than a car this price should have but that the exterior styling was excellent. “At least Chevy’s designers penned an aggressive body that’s a clean brake (sic) from the usual jellybean hybrid,” he wrote. “We’d buy the car on looks alone.” The author said the car actually looked more aggressively than its performance was capable.

Now to the question we’ve all been waiting for.

The reviewer took the car through three full recharge cycles. He was able to get 31, 35, and 33 miles of EV range, for a total average of 33 miles. This included one drive of 78 MPG highway in which the 33 mile range was achieved.

The driver specifically determined fuel economy after the battery was depleted and while in extended range mode.

“In the city, we recorded 31.67 mpg and achieved 36.0 mpg on the highway,” they wrote.

In the end the reviewer found the car a well engineered car that was surprising refined and capable of being a primary vehicle that does not restrict the driver to a fixed  EV range. “Consider the Volt a well-engineered first step on the path to electrified vehicles,” he wrote.

Tomorrow I will have my chance to test this out. Remember your mileage will vary.

Source (Popular Mechanics)

As the timeline moves closer and closer to the November 11th Job 1 date, GM is ramping up the marketing machinery.

I will be going back to Detroit on 10/11 for a day of extensive Volt driving on the roads of Michigan as well as attending extensive technical presentations about the car.

It is my understanding that all of the Volt’s last secrets will be laid bare for the world to see.

“Over the course of the next couple weeks, more than 150 media members will visit southeast Michigan to drive Volts significant distances, over varying terrains and if I know Michigan, in various temperatures,” writes Volt vehicle line director Tony Posawatz in a blog post. “These journalists and bloggers will learn intimate details about the Volt from the men and women who have been diligently working on this program.”

“And although we’ve given you a great deal of information during the past few years as part of the Volt’s open and transparent development,” he promises. “All the pieces of the puzzle will come together to showcase the Volt’s full capabilities.”

GM will also be launching its nationwide Volt Unplugged tour during which consumers will get to test drive the car. If you’re going to one, please log into our dedicated forum thread, and arrange meetups with your fellow Volt fans.

Posawatz concludes his comments about the upcoming flurry of Volt activity culminating in the first consumer car with the following words of hope:

We started something back in 2007. This is a long and winding path and we’re nowhere near the end of the journey. I believe this is just the beginning.

For fun you might wish to read my original Q and A with Tony back in late 2007, and if you have any new questions you want me to get answered while I’m there, place them in this forum thread.

Source (GM)