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.

GM's MyLink. Credit: GM

A key problem with adding computer-like functionality to your car's dashboard is that, because of the long, multiyear lead times for developing cars, interfaces and functionality tend to be outdated as soon as the car rolls of the production line, and will be hopelessly clunky by the time you've had the car for five years.

Ford partially addressed this with its Sync system, which uses Bluetooth to connect the driver's smart phone to the car's speakers, and which uses voice activation to make calls. GM recently announced a similar system, called MyLink. At CES this week GM announced that My Link will be available on its 2013 Sonic and its 2013 Spark EV. Such systems are as up to date as the driver's phones, in theory.

But with both systems you're still stuck with the built-in touch screen. Key characteristics—the responsiveness, multitouch ability, and the clarity, resolution, and brightness of the screen—will always lag behind the latest offerings from smart phone manufacturers and devices such as the iPad. And you've got to learn how to navigate the car's system and go through the process of pairing your devices. Similarly, if the system relies on the car's built-in microprocessors for voice recognition, this is bound to seem slow compared to the latest Siri-like applications on personal devices.

Why not just provide a versatile mounting station for whatever device a person owns to replace the car's touch screen? If a driver doesn't own one, throw one in with the financing of the car—it would be a relatively cheap add-on. Of course, it would be challenging to design this so that it doesn't look ugly—a station big enough to hold an iPad could look strange holding an iPhone. But it's worth the effort to make a drivers' expensive cars feel as up to date as the relatively cheap device in their pockets.

The automaker's know that consumers want this: "Customers all over the world told us they've set up their smart phones exactly how they want them, and the ideal car radio should extend the capabilities of their smartphone rather than try to duplicate them," said Sara LeBlanc, GM global infotainment program manager, in a press release this week. LeBlanc said GM has answered this desire with MyLink, but that's only a partial solution.

MyLink and Sync are about allowing drivers to access some of their smart phones' functions. The next step is allowing devices to make use of information from the car's internal network, such as steering wheel angle, GPS information, and vehicle speed, or even engine data and controls. For more on that, see, "Ford Bets on the Digital Car."

The plug-in Prius. Credit: NAIAS

Nissan and GM have been at the center of attention when it comes to electric vehicles, with the first sales of the Chevrolet Volt and Nissan Leaf last month, but now Ford and Toyota are weighing in.

At the Consumer Electronics Show last week and the North American International Auto Show in Detroit this week, Ford has officially unveiled the electric Ford Focus, which will go on sale late this year, along with new hybrid and plug-in hybrid vehicles, which will go on sale next year. The plug-in hybrid will travel farther than a conventional hybrid under electric power alone, but Ford isn't saying how far.

In Detroit Toyota revealed its plans for a family of Prius hybrid vehicles, which includes a plug-in version of the car (due next year), a larger version of the Prius (Prius v, on sale later this year) and a smaller one (Prius c concept).

Toyota's plan to stick with the successful Prius platform could be wise, as we argue here. These cars (including the plug-in version) use smaller batteries than the Leaf or the Volt, which makes them cheaper.

BYD, the Chinese automaker made famous by an investment from Warren Buffet, says it plans to start selling electric cars in the United States next year, after failing to deliver on a promise to sell the vehicle last year.