So Exactly What is a Volt?

By now, you’ve probably heard about the Volt. It’s Chevy’s (hopefully) upcoming “extended range electric vehicle” (EREV). To the average person, this is a hybrid, if you think of a hybrid as a vehicle that runs on battery and “traditional” (gasoline or Diesel) power. SAE (the Society of Automotive Engineers) also classifies it as a hybrid. GM wants you to think of this vehicle otherwise. The difference between the Volt and a hybrid as you know them is largely academic to the average customer. You should think of the Volt as a different kind of hybrid. It still runs on battery and gasoline, like the Escape or Prius, but the Volt will be able to run up to 40 miles on battery alone. Current hybrids can run on battery alone only in low-speed situations and for only a short time (“strong” hybrids from Ford, Toyota and some GM hybrids). Some can’t run on battery alone at all (“mild” hybrids from Honda and the other GM hybrids) – the battery only “helps” the gasoline engine. The strong hybrids improve fuel economy more, but also cost more. Now along comes the Volt, which is even more effective, but will also cost even more. To understand why the Volt is different, you need to understand the others as well.

Mild Hybrids
In a mild hybrid, the battery helps the engine propel the car, thus saving fuel. Regenerative braking charges the battery. This means the car is able to take the car’s kinetic energy, which is usually lost as heat when the car brakes, and use it to charge the battery. Mild hybrids also shut the motor down at a stop, saving more fuel.

Strong Hybrids
Though there are various types, strong hybrids are able to propel the vehicle by battery alone, albeit for short distances and low speeds. The battery also provides extra power when strong acceleration is required. Because the battery is used much more than in the mild hybrid, the strong hybrid improves fuel economy more, but also costs more. Strong hybrids are sometimes known as parallel hybrids, because both propulsion systems work together to propel the vehicle. The battery is charged by regenerative braking, but also by the car’s engine in normal use. Many strong hybrids have the unique trait of higher city fuel economy than highway. How can that be? In stop and go city driving, the battery is doing most of the work, so the improvement in fuel economy is much greater, resulting in better economy in the city. Some strong hybrids are “tuned” for power, rather than fuel economy. In these cases, the battery is used more to provide extra power than to ease the burden of the gas engine. You still get better fuel economy, just not as much.

Plug-in Hybrids
Though none yet exist for sale, a plug-in hybrid is a strong hybrid that you can also charge by plugging it in at home. The advantage is that you don’t need to use fuel to charge the battery; it starts out charged from your home electricity. Several automakers are working on developing plug-in hybrids for sale.

Series Hybrids
Though it is not called a hybrid, the Chevrolet Volt is a series hybrid. This is different from a parallel because instead of the 2 power sources working together, but separately, to propel the vehicle (“in parallel”), they work in-line. Only the battery powers the wheels, and in the Volt, it can do so for 40 miles when fully charged. The gasoline engine serves only to provide additional power to the battery when it runs out of power. It does not provide any propulsion. Because of this major difference from other hybrids, GM wants you (and the EPA) to call the Volt and electric vehicle, because the car really runs on electric only. The gas engine is merely a generator for the battery.

This all brings up a question: how do you measure and rate the fuel economy of a car that might never use any fuel? GM claims that 80% of drivers commute less than the 40-mile electric-only range of the Volt. In theory, they would never need to fill up the tank with gas if they remember to charge the battery every night. GM also claims that the Volt will get up to 50 MPG while the engine is running after the battery is drained. So what’s a poor government agency to do? Is the MPG infinite? 50? Something in between? The California Air Resources Board (CARB) has proposed using an SAE standard from 1999. The worst-case scenario is the battery is dead, so you drive 100% with the gas engine running; the best is fully charged and you never need gas. CARB suggests averaging the 2, so if the worst case were 40 MPG, then the “official” MPG would be 80. This idea has merit, but the 80 MPG in this example is theoretical only. A “real” driver would almost certainly never get the 80 MPG. You could also say that about “regular” cars today, but at least the EPA standard is close in almost all circumstances. You can’t say that about the CARB idea. Have a better idea for GM and the EPA? Send your ideas to The Slandy Report, and we’ll pass them along.

So will the Volt change the auto industry, as some claim? In a word, maybe. If the battery performs as hoped. If it is reliable. If you can really travel 40 miles with no gas. If it isn’t overpriced. If it launches on time. The General has really gone out on a limb with the Volt. I believe it is unprecedented to reveal a car more than 2 years before it is supposed to launch. I believe it is also unprecedented to make such bold, specific claims about a technology that doesn’t even exist yet in a commercially viable form. GM has staked its already shaky reputation on the Volt. If it doesn’t deliver on the claims, it could be a setback from which it cannot recover. Several clichés come to mind, including “You live by the sword, you die by the sword.” For the GM’s sake, I hope the sword is friendly (or really soft material).

Present Hybrids for Sale and Their EPA Fuel Economies (City/Hwy)
Mild Hybrids
Chevrolet Malibu 24/32
Honda Civic 40/45
Saturn Aura 24/32
Saturn Vue 25/32

Strong Hybrids
Cadillac Escalade
Chevrolet Tahoe 21/22 RWD or 20/20 4WD
Chrysler Aspen – TBD
Dodge Durango – TBD
Ford Escape 34/30 FWD or 29/27 AWD
GMC Yukon 21/22 RWD or 20/20 4WD
Mercury Mariner 34/30 FWD or 29/27 AWD
Lexus 600h L 20/22
Lexus RX400h 27/24 FWD or 26/24 AWD
Lexus GS450h 22/25
Mazda Tribute 34/30 FWD or 29/27 AWD
Nissan Altima 35/33
Saturn Vue 2-mode
Toyota Camry 33/34
Toyota Highlander 27/25
Toyota Prius 48/45

Plug-in Hybrids
None

Series Hybrids
None

Future Hybrids
Mild Hybrids
2010 Honda Insight

Strong Hybrids
2009 Saturn Vue “2-mode”
2009 Chevrolet Silverado
2010 Dodge Ram
2009 GMC Sierra
Ford Fusion
Mercury Milan

Plug-in Hybrids
Toyota Prius

Series Hybrids
2011 Chevrolet Volt