Whatever you've heard about the electric car, it is plug-in hybrids that will lead the way. That's the emerging consensus from  the wide-ranging “The Business of Plugging In” conference in Detroit this week. As automotive, technology, and policy experts share their perspectives at this industry event, there is much agreement that plug-in hybrids (PHEVs) are a necessary intermediate step on the road to pure battery-electric cars. Plug-in hybrids have one obvious advantage over other purely electric cars and some that aren’t so obvious. (See our test of the converted Prius plug-in.)

The obvious advantage is that plug-in hybrids have an internal combustion engine that eliminates concerns about electric cars’ limited range. You can drive a plug-in hybrid anywhere gasoline is available—even places without recharging stations.
 
The best-known plug-in hybrid coming down the road is the Chevrolet Volt. This sedan uses a large 16-kWh battery pack, and GM claims a 40-mile driving range on electric power alone. And it has a gasoline engine  that acts as a generator to provide electricity to drive the electric motor for longer trips. The farther you drive it without plugging in, the more of the time you’re likely to run on plain old-fashioned gasoline, even though that engine does not send its power directly to the wheels. 
 
Range anxiety
A study by the Japanese Ministry of Transport showed that when a fleet of electric-car drivers had only one charging station to use, they were only comfortable using just half their cars’ range. When a second station was installed at the end of those existing trips, drivers went farther and used virtually all of their cars’ range. But they almost never charged at the second station. It was important for them to know it was there just in case they needed it.
 
That leads to the second benefit of plug-in hybrids over pure battery-electric vehicles: They don’t necessarily require any additional infrastructure. One of the big debates in the electric-vehicle community is whether electric vehicles will necessitate some costly new infrastructure, such as a nationwide network of high-voltage charging or battery-swap stations, or whether home recharging facilities will be all that’s needed.
 
One of the main advantages of any electric car, plug-in or pure battery, is that they can recharge when power demand is low and the grid is underutilized, such as at night. But as the Japanese case showed, that won’t be enough if people are afraid they won’t be able to get a recharge in a pinch. 
 
Another benefit of the plug-in hybrid is that their expected popularity--and a growing population of drivers wanting to maximize the miles they travel on electricity alone--will provide an incentive for companies (or municipalities) to build charging stations ahead of pure EVs going mainstream.
 
Plug-ins aren’t stopping several automakers from rolling forward with all-electric cars. BMW is already leasing the Mini-E, electric car, Ford plans to roll out all-electric versions of the Transit Connect minivan and Focus small car next spring, and Nissan plans to introduce the all-electric Leaf in Japan next fall.
 
Now automakers have the flexibility to meet it by selling relatively few electric cars, or greater numbers of plug-in hybrids. Automakers can also trade in credits they’ve earned for building PZEV (ultra-clean) gasoline cars and other forms of electric vehicle before the regulations take effect. The mandate starts phasing in between 2011 and 2014. Those next few crucial years will give us a better idea whether plug-in hybrids or pure electric vehicles are more likely to earn space in consumers’ garages anytime soon.

—Eric Evarts

Learn about driving green in the Consumer Reports special fuel economy section.