By on June 28, 2010

Accelerating up the motorway slip road, the Ampera charges hard and deceptively quickly up to 50mph, but by then the single-speed electric motor’s flat torque curve has begun a nose dive and acceleration at high speeds is poor.

The 0-62mph time of 9 seconds and top speed of 100mph are an indication of this – most family hatchbacks with that sort of sprint capability will have a top speed of nearer 130mph

The Telegraph‘s Andrew English lays into the Chevy Volt/Opel Ampera’s high-speed acceleration, in an early test drive on European roads. Apparently an Opel engineer was embarassed enough by the performance to tell English that

We are considering driving the wheels directly from the petrol engine

Huh?

Opel’s Andreas Voight continues on this unexpected theme, telling English:

There are a number of different ways we could do it, but the whole thing is subject to some intellectual property rights negotiations so I can’t say any more. You will see an announcement this autumn

Except that GM already has a two-mode “parallel” hybrid drivetrain, and the Volt has been presented as an extended-range EV. Allowing the gas engine to power the wheels would be a fundamental repudiation of everything the Volt is supposed to be.

Luckily gm-volt.com was on-hand to help The General get on top of this nasty development. Via the independent website, GM’s spokesfolks say

This report is inaccurate. First off, the Volt cannot be driven without electric power. It always makes use of electric power within the drive unit.

Secondly, we have no plans to make any mechanical or control strategy changes prior to launch.

The team is in the final stages of validation and durability and have not identified any reason to make any changes. We have a very innovative drive unit that includes a number of clutches and a planetary gear-set which is highly efficient and exists in our pre-production vehicles today. For competitive reasons we won’t provide more details on the operation at this point, but will soon.

Notice that GM does not comment on the Volt’s high-speed performance, and has not officially allowed reporters to drive a Volt over 50 MPH yet (although there is a rumor of someone hitting 92 MPH in a Volt). So, how will the Volt perform at freeway speeds? Though some argue that freeway performance for the Volt is irrelevant, the reality is that Chevy designed the Volt around the idea that it could be used as a single-family car. After all, what’s the point of eliminating range anxiety if the Volt isn’t up to long freeway jaunts at speed?

The answer to the problem: weigh less than 3800 lbs. But how?

[Want more answers than questions... check out Consumer Reports' test of a pre-production Volt]

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18 Comments on “Quote Of The Day: Volt In Need Of A Jolt? Edition...”


  • avatar
    daga

    Probably just a brain fart from someone on the ground. Also sounds like something that could be solved with gearing if need be

    • 0 avatar
      LastResort

      Sounds like they run out of the constant torque region into the constant power region. “Fixing” this through gearing would require trading off the torque, increasing the 0-60 MPH time.

    • 0 avatar
      vww12

      Reminds me of the smart electric drive, governed at 62 MPH and with a Tesla powertrain.

      I had thought they had limited it to 62 MPH because of battery performance issues, but I’m now thinking they may also be struggling with horsepower issues, as LastResort writes. They’d rather (1) extend their battery range and (2) not have to explain their vehicle is underpowered. Instead, with 62 MPH any reviewers and testers can fall back on “oh it’s peppy.”

      Gasoline smarts are governed at 93 MPH.

  • avatar
    jmo

    Doesn’t the speed limiter kick in at 97mph on a Tahoe or Suburban?

  • avatar
    TR4

    It seems like the Volt has a fairly modest power-to-weight ratio in today’s context hence the modest acceleration > 50 mph should not be surprising. I can’t find any weight spec but let’s assume it’s 3000 lbs. The (electric) horsepower is typically quoted as around 150. So we have each horsepower trying to accelerate 20 lbs. Decent numbers 50 years ago but hardly impressive now.

  • avatar
    bumpy ii

    Considering that the Cruze itself is over 3,000 pounds, I think the Volt will end up being more like 3,500 pounds and 3,600 or 3,700 wouldn’t surprise me. GM seems to have cornered the market on anti-Chapmanite.

  • avatar
    ChesterChi

    It’s not competing with a Corvette, who cares about 0-60 for a commuter car like this ?

  • avatar
    John Horner

    ” … but by then the single-speed electric motor’s flat torque curve has begun a nose dive … ”

    “We have a very innovative drive unit that includes a number of clutches and a planetary gear-set which is highly efficient and exists in our pre-production vehicles today.”

    I’m confused. Is there a variable ratio transmission of some kind between the Volt’s electric motor and the driven wheels or not? The “planetary gear-set” phrase brings to mind some sort of automatic transmission, but the earlier quote seems to imply that the Volt is a one gear ratio only machine. Which is it then?

    To the main point, if the Volt cannot accelerate to, and cruise comfortably at, California freeway speeds than it is useless for most of its potential customers. At least the Volt does have the ability to keep running long after leaving the electric docking station. A vehicle like the Leaf which could potentially become a door stop after 100 miles or so is completely uninteresting.

  • avatar
    Robert Schwartz

    “Allowing the gas engine to power the wheels would be a fundamental repudiation of everything the Volt is supposed to be.”

    And what is the Volt supposed to be?

    My take was that it was supposed to be cover for the Government Money.

  • avatar
    Hank

    In my line of work we constantly look for “key phrases” in any writing we are analyzing. While I doubt it means much, the key phrase from the GM spokesperson that jumped out to me was “prior to launch.”

  • avatar
    Michal

    Where in the USA is it legal to drive 100mph? Race tracks and private roads not included. The top speed is likely to only be a psychological barrier for customers, rather than a real one.

  • avatar

    Perhaps later versions will be both serial and parallel hybrids but for the time being I call bullshit at least in terms of “an announcement in the autumn”. The Volt’s already past validation and now they’re building pre-production units on the assy line in Hamtramck, working out the kinks of production. There’s simply no time to completely reengineer the car, which is what the story would involve, since the ICE is not currently physically connected to the transmission, and in any case, the ICE’s been optimized to run at steady speeds running a generator, not the variable loads of mechanically driving the car. Trying to make it do both would be at cross odds to efficient operation.

    Like I said, there’s just so much knot twisting in this story that I think it’s a big nothingburger.

    Just because GM fucked up under repeated managements and now is on the government dole is not reason enough to not believe that one of their competitors might try to spread disinformation. You think Carlos Ghosn isn’t cutthroat enough to have a story like this planted?

  • avatar
    Zarf

    Who is the target market for this thing?
    With 70 being the highest posted limit that I know of in the states I don’t see the problem.
    Nine seconds to 60 isn’t going to intimidate anyone looking for a race but it isn’t that out of line by today’s economy car standards.

    In fact it always confuses me when I’m cruising along at 65 or 70 and a Fit or Prius go past me at 90 or 100. I see cars like this being bought for efficiency and at those speeds the engines are probably screaming for mercy. I could be wrong though.

    • 0 avatar
      educatordan

      75 is the posted limit on sections of Interstate Hwy out West. And just having driven the corridor between Albuquerque and Gallup, 85mph is keeping up with most of the traffic. I even got passed with good regularity.

      Now if I can easily make that trip in a 5 year old Pontiac Vibe with the smallest available engine and a standard shift but not in a $40,000 compact car, then in my mind the Volt fails.

    • 0 avatar
      JeremyR

      As Dan points out, much of the West has posted speed limits of 75 MPH. I will add that I’ve seen 80 MPH posted in parts of west Texas.

  • avatar
    Contrarian

    Low stock prices are more likely to blow the Volt launch.


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