Video Hints At Volt Performance: Just Over 40 Miles Of EV Range, Under 30 MPG Thereafter

Edward Niedermeyer
by Edward Niedermeyer

TTAC has a long, proud tradition of tearing into puffy automotive journalism, so it was not without a little trepidation that I wrote in the comments section of Michael Karesh’s excellent review of Zero To Sixty that

Toothless reporters put execs at their ease… which allows them to say naive or revealing things that toothy bloggers can then rip into. In a weird way, the worse the reporter, the better the reporting (as long as the quotes are then duly digested). As time goes on, I find myself more and more at peace with this evolving media food chain… and TTAC’s place in it.

To be clear, this is not an endorsement of toothless coverage per se, it’s just a pragmatic response to the reality that auto industry coverage will continue to be dominated by PR-approved puff. And this video provides yet more proof that non-threatening journalists are actually the most effective at snagging scoops, even if they’re totally unaware of said scoop. Which is where the bloggers come in.

AOL Autos’ TransLogic was invited to Milford Proving Grounds for a PR-guided tour of the Volt, and in the process accidentally reveals one of the few still-guarded secrets about the Volt’s performance: post-EV-range, or “Charge Sustaining Mode” (CS Mode) efficiency. Speculation has been rampant about what kind of mileage the Volt gets after exhausting its 40-mile electric range, with guesses ranging from 30 MPG to 50 MPG. And though the video shows that TransLogic was able to get the Volt to 43 miles on electric range, it also shows that, as gm-volt.com reports,

The car then traveled an additional 16.1 miles using .59 gallons of gas for an average real-world MPG of 27.3 MPG.

Now, 16 miles isn’t exactly a definitive test, nor do we know exactly how the 16 miles was driven. Besides, GM would surely argue that the Volt tested was not a true production model, and that drawing inferences from this inadvertent information nuglet is premature. Still, they’re the ones concealing the Volt’s CS Mode performance, and if sub 30 MPG performance is what we can expect, the decision to keep the number under wraps is completely understandable. After all, that’s hardly an eco-friendly number coming from the Volt’s main claimed competitive advantage over the Nissan Leaf, namely its gas range-extender. With the “230 MPG” fiasco still festering, and GM and the EPA “negotiating” a fuel economy window sticker that is likely to be unique to the Volt (at least for now), we have to wonder how truthful GM plans on being about the Volt’s CS Mode efficiency.

Here’s hoping we learn more soon via a tough question honestly answered, rather than through an inadvertent leak by way of a breathless video report… but who’s holding their breath for that?


Edward Niedermeyer
Edward Niedermeyer

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  • Musiccitymafia Musiccitymafia on Aug 27, 2010

    I’m still struggling with the “4-5 times more efficient” statement. So I’m going to question it. Apologies for the in-elegance of my logic. Usage of a Petroleum power generating plant allows an apples-to-apples comparison. Let the utilities figure out what fuel they want to use to maximise profits. Side-observation – the utilities should make out alright selling excess electricity to EVs in the middle of the night without incurring additional costs. Here we go with my clumsy analysis/assumptions/conclusions: 1. Assume a generous 35% average efficiency for the power plants (see petroleum, coal, hydro, or nuclear efficiencies referred to in one of TimCrothers’ links above) 2. Assume 6.5% for losses purely in transmission from the power plant to residences. I don’t know how this was calculated because I don’t think utilities rack-and-stack all the usage numbers from each individual customer/residence, but people seem to think it's reasonable. 3. Assume EV uses 8 kWh of electricity to drive 45 miles daily 4. Assume ICE uses 1 gallon of gas to drive same 45 miles daily Lets go with a Prius since it’s an ICE vehicle with “stuff added” to make it more efficient … over time more efficiencies will be found … but that’s where we are today …. this “stuff” could be added to an EV if desired. 5. Assume 90% for efficiency of chemical batteries and electric motor in EV that convert the electric energy into usable mechanical energy to drive the vehicle. Yup, I made up this number based on thin air … but it’s really not that important wrt questioning the “4-5 times more efficient” statement so don’t get stuck on it. 6. Assume 30% for the efficiency of the gas motor in the ICE that converts the petroleum energy into usable mechanical energy to drive the vehicle. Seems reasonable since petroleum power plants are 31.1% efficient as provided by TimCrothers’ links above … other inefficiencies of a vehicle as it runs down the road are additional and also suffered by the EV (some may say less so because it's a simpler powertrain). In other words, assume the EV and ICE are similar weight and size rolling on similar tires with similar drag coefficients etc etc. Yeah, the ICE is probably not quite as efficient at getting it’s mechanical energy down to the wheels … but wrt questioning the “4-5 times more efficient” statement this assumption seems reasonable. 7. Assume the EV needs the same amount of mechanical energy (after it’s pulled out of the batteries and converted) as the ICE does (after it’s exploded out of the fuel and converted) to propel the vehicle over the same daily distance. OK, NOW FOR MY SIMPLE ANALYSIS Start at the point where the mechanical energy becomes available … it’s right after the gas motor in the ICE or the electric motor in the EV. The ICE needs all the mechanical energy that can be converted from 100% of the Btu’s in 0.30 gallons of fuel to drive the 45 miles. Due to the inefficiency of the gas engine it hence needs 1.0 gallon of fuel in its tank to get this amount. This means 1.0 gallon of fuel needs to come from the oil refinery. The EV also needs all the mechanical energy that can be converted from 100% of the Btu’s in 0.30 gallons of fuel (Assumption 7) . We’ve been lead to believe that 8 kWh of electricity in the batteries will provide this amount. Some simple math and using the 6.5% transmission loss and 35% power plant efficiency says 1.02 gallons of fuel need to come out of the oil refinery. CONCLUSION I don’t see a significant efficiency difference between EV and ICE … and quibbling about this or that assumption will have marginal effect. Then there’s the fact that most of the explosive power in gas remains intact between the time it’s extracted from the ground until it’s put into an ICE vehicle. Conversely most of the energy in a lump of coal (or whatever medium you chose) has been lost before it gets into an EV in the form of household electricity. Now, there are advantages to an EV such as the capability to use renewable fuels, using power plant energy that was maybe going to waste anyway, getting people to drive smaller vehicles, and so on. But the "4-5 times more efficient" ain't one of them if the conversation is about fuel.

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    • TimCrothers TimCrothers on Aug 27, 2010

      Now try this musiccitymafia: Petrol is $2.70 a gallon in the US average http://gasbuddy.com/ Electricity is $0.0981 per kWh in the US average http://www.eia.doe.gov/cneaf/electricity/epm/table5_3.html Camry ICE (4cyl/6auto) gets 26mpg EPA Prius hybrid gets 50mpg EPA Volt hybrid gets 45 miles per 8kWh Leaf EV gets 45 miles per 5.5kWh Cost to drive 45 miles: Camry $4.67 Prius $2.43 Volt $0.78 Leaf $0.54 The Prius is 52% the cost of a Camry The Volt is 16% the cost of a Camry The Leaf is 11.5% the cost of a Camry The Volt is 32% the cost of a Prius The Leaf is 22% the cost of a Prius The Volt is 6.25 times as cheap as the Camry The Leaf is 8.6 times as cheap as the Camry The Volt is 3.15 times as cheap as the Prius The Leaf is 4.5 times as cheap as the Prius

  • Musiccitymafia Musiccitymafia on Aug 27, 2010

    WRT efficiency: An ICE vehicle is not efficient using fuel that's put into it .... but the fuel that's put into it contains most of the energy it originally had. The EV is efficient using it's fuel .... unfortunately creating the EV's electric fuel has resulted in losing the majority of the energy contained in the original fuel (petrol, coal, whatever). Some say only 30% remains. Stating that one is 4-5 times more efficient than the other is incorrect. If only because without using the same fuel source it cannot be calculated. If the same source is used it's probably pretty close. WRT Emissions - still don't know. If using the same fuel source probably pretty close only power plant vs tailpipe. WRT Costs - EV's using excess fuel generated by power plants or subsidized by the government will win hand's down. Unfortunately at present these costs do not include a lot of costs to the environment (for instance what are we doing with spent fuel rods?).

    • See 1 previous
    • Musiccitymafia Musiccitymafia on Aug 29, 2010

      My comments and opinions are unchanged.

  • MaintenanceCosts It's not a Benz or a Jag / it's a 5-0 with a rag /And I don't wanna brag / but I could never be stag
  • 3-On-The-Tree Son has a 2016 Mustang GT 5.0 and I have a 2009 C6 Corvette LS3 6spd. And on paper they are pretty close.
  • 3-On-The-Tree Same as the Land Cruiser, emissions. I have a 1985 FJ60 Land Cruiser and it’s a beast off-roading.
  • CanadaCraig I would like for this anniversary special to be a bare-bones Plain-Jane model offered in Dynasty Green and Vintage Burgundy.
  • ToolGuy Ford is good at drifting all right... 😉
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