The next generation of hybrids will feature lithium-ion battery packs instead of the nickel hydride batteries currently powering hybrid vehicles. Though these new batteries are heavier and more expensive, they’re the key to longer range electric-only drive cycles which are expected to double current hybrid fuel economy. Many plug-in electric cars will take seven or eight hours to charge an empty battery, though the Volt will charge en empty battery in 3.5 hours using a 220v outlet.

Not to be outdone by the recent green car convert, Toyota is eyeing the same goal with a plug-in version of the uber-efficient Prius in 2010. Armed with an aerodynamic body and lightweight construction, the plug-in version of this fuel sipper should retain its “most fuel efficient” title. However, it won’t be doing it with lithium-ion batteries. The plug-in Prius that is currently being tested operates with dual nickel-hydride batteries, and it can achieve a pure EV range of approximately seven miles at a top speed of about 63 miles per hour.

If a plug-in hybrid is good, Nissan and Mitsubishi think all-electric is even better. These carmakers are promising an all-electric car, but both are coy about the details. Mitsubishi will begin fleet testing its cutesy MiEV (Mitsubishi innovative Electric Vehicle) in California this year, with the expectation that it'll begin consumer sales of the vehicle. The MiEV is scheduled to go on sale in Japan in 2009.

Though details are scarce, Nissan has announced plans to build an all-electric vehicle, and it swears it’s not the upcoming Cube. The yet-to-be-determined electric vehicle will be designed from the ground up as an electric vehicle, rather than by sticking an electric powertrain in an existing production vehicle. Much of the technology will be borrowed from the Nissan Hypermini, an electric vehicle that has been tested in Japan since 2000. And if the Hypermini is any indication of what the vehicle will look like, expect a small, cute, button of a car.

While the charging infrastructure has some catching up to do (imagine what would happen if 100,000 electric cars all plugged in at the same time during the summer in Los Angeles), interest in these cars is surging. GM is working with more than 30 electric companies to develop an in-home charging station that will use software to delay recharging the battery until off-peak hours, and many cities are mapping out where to install electric “fueling” stations.

Given the pace of government-backed development projects, it may be best to start investing in a few hundred feet of power cords that you can keep in the trunk. The good news is that any 110v power outlet will do the trick. But don’t hurry to the showrooms just yet or run extension cords to your garage – with the exception of the Tesla Roadster, electric vehicles and plug-in hybrids are still a few years away.

Chevrolet Volt
Type: Plug-in hybrid
ETA: 2010
The only carmaker to announce a specific car and production time frame, Chevrolet anticipates the first commercial electric car to roll off the production line in 2010. Designed from the wheels up to be a plug-in hybrid, the Volt is estimated to deliver a 40-mile range from the 16-kwh lithium-ion battery pack (still being tested). The Volt will also sport a 1.4L gas engine that kicks in to create additional electricity  when the electric battery is drained.

Saturn Vue Plug-in Hybrid
Type: Plug-in hybrid
ETA: 2010
Like its cousin, the Chevy Volt, the Saturn Vue will be available as a plug-in hybrid around the same time the Volt hits the streets. However, the Saturn Vue will use a smaller lithium-ion battery (still in testing) than the Volt, which is designed to fit around the SUV’s current frame and transmission. But the new, energy-dense battery is still big enough to power the popular crossover for the first 10 miles or so, and it will also sport a gas engine that will recharge the battery. While there are no official numbers, the plug-in hybrid version of the Saturn Vue is expected to double the mileage of the two-mode hybrid Vue that is due later this year. The Saturn Vue two-mode hybrid is expected to achieve a combined fuel economy of 30 miles per gallon, which – stay with us – means that the Saturn Vue Plug-in Hybrid should have a combined fuel economy of approximately 60 mpg.

Toyota Prius
Type: Plug-in hybrid
ETA: 2010
If you’ve been eyeing plug-in conversion kits for your Prius, stash away that $10,000 and use it as a down payment on the upcoming Prius plug-in hybrid. Expected to debut in 2010 for fleet testing and then make its way to consumers a year or so later (which is still earlier than the timeframe it will take to recoup the $10,000 you spend converting your current Prius to a plug-in), the Prius plug-in hybrid is currently being tested with two nickel hydride batteries rather than a trendy lithium-ion battery. Although the current product is continually being improved, the prototype currently can operate 6-7 miles in EV mode at a top speed of approximately 62 mph. Improvements are expected before its official debut, but the plug-in version of the Prius is rumored to more than triple the current mileage. Unofficial records of aftermarket Prius plug-in conversions (which are not warranted by Toyota) by Google’s RechargeIT Driving Experiment report fuel economy of 93.5 mpg.

Nissan TBD
Type: Electric
ETA: 2012
They know it’s electric, and they know it’ll be for sale in 2012, but that’s all Nissan representatives  will say. That, and that it’s not the Nissan Cube. Rumors of the electric Cube began when it debuted as a concept car at the 2008 New York Auto Show. While we can officially cross the Cube off the list of possible electrics in 2012, Nissan is promising a vehicle designed from the ground up as an electric car instead of a production car with an electric motor dropped in it. It's also hinted that it's going to be borrowing heavily from its concept electric car, the Hypermini, which has been tested in Japan. Fleet testing is expected to begin in 2010, and whatever it is will be available to the public two years after that.

Mitsubishi i MiEV
Type: Electric vehicle
ETA: 2010, 2011-ish
This four seater electric car powered by a 330-volt lithium ion battery is currently being fleet tested in Japan and is expected to go into production in 2009. With a top speed of 130 km/h and a range of 80 miles (based on the Japanese 10-15 low-speed driving pattern) on a single charge, the i MiEV will be fleet tested in the US by PG&E and Southern California Edison. If all goes well with the fleet tests, battery production issues are solved, and there’s sufficient demand, U.S. consumers may see the car for sale in the US in 2010.

Tesla Roadster
Type: Electric vehicle
ETA: Now
It’s by no means a car of the people, but the Tesla Roadster is one of the few electric cars that you can buy today. The $109,000 two-gear sports car can launch from 0-60 mph in 3.9 seconds, and its curvy body based on the Lotus Elise proves that environmentally friendly can also be sexy. It advertises a 220-mile range on its lithium-ion battery back that takes 3.5 hours to charge.

Mini Cooper
Type: Electric
ETA: Leasing in 2009
One of the most fuel efficient non-hybrid vehicles will be swapping its internal combustion engine for an all-electric drivetrain. Starting in 2009, BMW Group will begin leasing 500 of this prototypical small car in California, with suspected plans to expand production across the country.