The Ford Fusion Energi. Credit: Ford

Ford unveiled its new Fusion Energi plug-in hybrid at the North American International Auto Show in Detroit this week. It didn't say much about the car, except that it will get something like 100 miles per gallon equivalent (MPGe), which is better than the Chevrolet Volt or the upcoming Toyota Prius plug-in, and that it will go on sale toward the end of this year.

Of course, 100 miles per gallon equivalent sounds impressive. Unfortunately, the MPGe figure is not very meaningful. It's useful as a way of comparing the efficiency of cars when they are operating in electric mode, but for a plug-in hybrid, which can run part time on gasoline, it doesn't tell drivers what they really want to know: how much gas the car will use and how much it will cost to operate.

According to the U.S. Environmental Protection Agency definition, MPGe is meant to describe the efficiency of the vehicle when operating using electricity alone, which in a plug-in hybrid is typically only a relatively short range—the Chevrolet Volt can go about 35 miles on the electricity stored in its battery. MPGe refers to how many miles the car can go on an amount of electricity equivalent to a gallon of gasoline.

Based on the figure of 100 MPGe, we know that the Fusion Energi will be slightly more efficient in electric mode than the Volt (93 MPGe) and the all-electric Leaf (99 MPGe).

But drivers need to know how far the car can go on electricity and under what conditions the gas engine will come on, to figure out how much gas they'd use. The Chevrolet Volt can go 35 miles on battery power before using the gas engine. The upcoming Toyota plug-in Prius will only get about a dozen miles on a charge. If your commute is 30 miles round trip, you could get away without using any gasoline with the Volt, but not with the Prius. If your commute is much longer than the Volt electric range, you may want to consider the Prius, which gets 49 miles per gallon after the electricity is gone, rather than 37 miles per gallon for the Volt.

So we don't know how far the Fusion Energi will go on battery power. We don't even know if it will be able to achieve highway speeds on electricity alone. And there's no way for drivers to know how much gas it would use, or whether it would make more or less sense to buy than its competitors.

Having a few electric vehicle charging stations here and there isn't a big deal. But if they ever become common in cities, they'll be an eyesore, with their long, tangled black cords clumped onto their sides or sprawling across parking spaces to the outlet on the side of a car. Charging stations could also be a tempting target for vandals.

A much more elegant solution would be to bury inductive chargers under parking spots, a concept that Daimler has started testing. The chargers could be invisible and protected from vandals. And they could make charging easier—just pull into a parking spot, and the car can start charging.

Daimler, along with Conductix-Wampfler, a company based in Germany, has only recently started testing cars equipped with the inductive charging coils. But the initial results look positive.

The system is 90 percent efficient, which isn't as good as charging with a cable, but is better than some other inductive charging systems. The companies say that when you count efficiency losses within the car, the system is almost as good as plugging in.

Daimler has modified a E-Cell plug-in hybrid concept vehicle like this one to allow it to charge without having to plug in. So what will we call plug-in hybrids now? Credit: Daimler

In initial tests, after two or three practice runs, drivers have been able to successfully park their cars so that they're centered over the charging coils.

An object detection system is supposed to avoid the potential problem of the buried coils heating up a piece of metal left on the road. The prototypes are based on a wireless charging system developed for electric buses that has been operating since 2003.

It will be interesting to see how the cost of the system compares to conventional chargers, and whether it will still be necessary to install a post for communications gear, to allow drivers to pay for the charge with their credit cards, for example. Ultimately, cities will have to decide whether the better looks and convenience are worth the sacrifice in energy efficiency.

The company WiTricity is developing chargers that could be more convenient still, charging efficiently at distances greater than is allowed by inductive charging. We featured the technology as one of our 10 Emerging Technologies of 2008.

In his State of the Union speech, Obama set a goal of putting one million "electric cars" on the road by 2015. He might not have meant to say it exactly that way. Indeed, a press release from the Department of Energy, giving details about the President's budget (which will come out in the middle of February), substituted "advanced technology vehicles" for "electric cars." Apparently, at least some hybrids (likely plug-in hybrids) will count toward this number. That's a good thing, because hitting a million electric vehicles in the U.S. by then sounds like a stretch. It took Toyota over 10 years to sell a million Priuses world wide. Electric cars have just started to be introduced, and they cost thousands more than hybrids like the Prius, which will likely slow their adoption. Plug-in hybrids can be cheaper, and they don't have the range limitations that could limit the market for pure EVs.

Here's how Obama hopes to reach his goal. First, the Recovery Act has already allocated $2 billion to help build factories for batteries another other electric car components, as well as $400 million for electric vehicle demonstration and infrastructure. Under the fiscal year 2012 budget, a tax credit worth up to $7,500 for plug-in hybrids and electric cars will become available as a rebate as soon as a car is bought--so people don't have to wait around for the tax return. The budget will also increase R&D spending for vehicle technology and for a fourth "energy innovation hub" focused on developing better batteries. And it will include fund 30 $10 million community projects geared towards making electric vehicles more attractive, by "regulatory streamlining, infrastructure investments, vehicle fleet conversions, deployment of EV incentives (e.g., parking, HOV access) partnerships with major employers/retailers, and workforce training."

Electric vehicles certainly need some help. Batteries are expensive, and the first mass-market electric cars, such as the Nissan Leaf, can't go very far on a charge. Public fast-charge stations could make the vehicles more convenient, and instant rebates could help sales. But getting funding increases past Congress when the House, in particular, is working to decrease government spending, could be difficult.