Plug-in hybrids expand electric-car market

Bridging powertrain technologies, plug-in hybrids may be the wave of the future, providing convenience, efficiency, and range. For now, price remains a hurdle to mainstream sales, but the technology itself works well and has tremendous potential.

Plug-in hybrids operate on a simple premise: Electricity is more efficient than gasoline, but gas offers longer range and quicker refueling for more driving flexibility. So by optimizing when it uses each power source the car can dramatically boost efficiency without sacrificing the ability to go anywhere any time that gas cars are known for.  Once the battery is depleted, the gas engine takes over to drive as far as you want. Some automakers thus refer to plug-in hybrids as "extended range electric vehicles." Given this extended range ability, plug-ins have smaller, less expensive battery packs than pure electric cars, and consequently, they don't take as long to charge. Buyers are also eligible for various tax credits up to $7,500.

Plug-in hybrids are expanding dramatically in the market.

• Debuting in 2012, the first widely available plug-in was the Chevrolet Volt. It can go about 35 miles exclusively on battery power, before the gas engine comes on and acts as an onboard generator. That ability could allow most drivers to commute all week without using any gas, as long as they recharge at night and/or during the day. The Volt costs about $40,000, before factoring the tax credit, but dealers often offer big discounts and lease deals are attractive.

• Toyota quickly followed suit with a plug-in version of the Prius. It uses a larger lithium-ion battery than the non-plug-in model, giving it a theoretical range of about 11 miles on electric power. Otherwise, it's identical to a regular Prius. Toyota says it can also go up to 62 mph on battery power. But in our experience, the electric power in the Prius Plug-in is more about boosting fuel economy than driving electrically. The gas engine runs frequently in normal driving conditions, and it starts with even mild acceleration or extra power demand such as climbing a hill. While the Prius Plug-in costs a little less than the Volt, it brings only a $2,500 tax credit.

• Ford also sells a plug-in version of its C-Max hybrid, called the C-Max Energi, with a 20-mile electric range. Unlike the Volt, the C-Max Energi can seat five. While the big lithium-ion battery takes up much of the cargo space, you can stack as much gear on top of it as you could put in a Volt. And we've found the C-Max Hybrid to be one of the nicest-driving hybrids on the market. A brief drive in the C-Max Energi left a similar impression.Unlike the Prius Plug-in, it was not hard to accelerate in the C-Max Energi and stay on electric power. It costs about $33,000, not counting a tax credit of $4,000.

• Honda offers a plug-in hybrid version of the impressive Accord sedan with a claimed 15-mile range on electricity, at speeds below about 50 mph. The battery, however, takes up about half of the trunk space. The Accord Plug-in has a quick 6.6-kW on-board charger that can recharge the battery in just under an hour. It costs about $40,000 and earns a tax credit of $3,626.

• General Motors has also introduced an upscale version of the Chevrolet Volt from Cadillac. Called the ELR, it offers all the same mechanical specs as the Volt, but in a sleek coupe body with all the latest luxury conveniences in a beautifully decked out interior. It's eligible for the same $7,500 tax credit, but you'll still have to write a really big check: The ELR stickers for $75,000 to start.
  

Another potential advantage of plug-in hybrids over pure electric cars is that their smaller batteries can be fully charged overnight on a standard household outlet. Therefore, you don't have to shell out another $1,000 to $2,000 for a dedicated 240-volt connector with installation, unless you want to be able to charge more quickly.

Automakers are still seeking the sweet spot in plug-in hybrids, looking for the right battery size to balance cost, charge times, and range. The good news for consumers is that that leaves plenty of variety, with more to come. Car buyers with shorter commutes can choose a model with a smaller battery and still minimize their gas usage. And even if the electric range falls a little short, a plug-in hybrid won't leave you stranded, removing a common concern with pure electric cars.

Going forward, consumers have an increasing array of options to meet their fuel economy and environmental concerns, ranging from an affordable-and-efficient traditional car to an all-electric model. 

See our guide to alternative fuels for more information about other fuel-efficient vehicles.