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.

General Motors is getting into the extremely fuel-efficient delivery van business with an investment in the startup Bright Automotive, it announced today. It's buying a minority stake in the start-up, which is developing a plug-in hybrid van aimed at fleet customers. The van can travel 38 miles on battery power alone, or it can act as a hybrid, combining gas and electric power to get 36 miles per gallon.

The vehicle seems to be a challenge to Ford's successful Transit Connect, a conventional gas or diesel powered delivery van that will be offered as an electric vehicle later this year. GM says that the Bright van has the advantage of having a longer range than the Ford electric vehicle, which can only go 80 miles on a charge. The Bright van has a range of about 400 miles when using both electric and gas power.

The Bright van also has an unusual hybrid arrangement. The front wheels will be powered by a gas engine (the engine and transmission will come from GM) and the rear wheels will be powered by an electric motor. Bright has developed control systems that coordinated between them.

When a battery company unveils new technology and brags about its long lifetime, the best industry analysts aren't necessarily impressed by charts showing voltage-current curves over hundreds or thousands of discharge cycles. "Show me the warranty," they say. That's a good indication of how long the company really thinks the battery will last.

GM executives have said they expect the battery for its upcoming Volt electric vehicle (actually, a type of plug-in hybrid) will last the life of the car. Now GM has backed up those claims (sort of) by announcing a 8-year, 100,000 mile battery warranty. That's not quite as long as I'd like a car to last--and not as good as a 10-year warranty some had expected--but it's a good amount of time compared to the 3-year warranty offered by some other manufacturers. Nissan, which is coming out with the electric Leaf this year, hasn't yet announced warranty details.

The battery warranty is key, since replacing a full battery pack could cost more than $10,000 by some estimates.