Despite the disappointments of Copenhagen, despite the inaction on climate-change regulation in Congress, despite the global recession, the momentum behind electric cars keeps building.

Yesterday, Better Place, the Silicon Valley-based electric car startup, raised $350 million in financing—the biggest clean tech investment ever, the company said, and a validation of a business model that has been scoffed at by the auto industry. The investment round, led by HSBC, values Better Place, which has yet to put a car on the road, at $1.25 billion.

“Electric vehicles are, at this point, inevitable,” said Jason Wolf, vice president of Better Place. “We’ve broken through, and there’s no turning back.”

Big automakers, meanwhile, are pushing forward with their electric offerings, as executives from Nissan and Ford affirmed yesterday during a “Green Car Summit” held at the U.S. Capitol.

Nissan Leaf

Nissan has been taking its all-electric Leaf, which will be introduced next fall, on a 24-city U.S. tour.  “The market is ready,” said Scott Becker, senior vice president of Nissan North America. “We’ve had an incredible reaction from consumers.” He said more than 38,000 people have signed up to get more information about the car.

“This is going to be a vehicle designed and made for the mass market,” Becker said. The car will have a range of about 100 miles before needing a new charge, good enough to meet the needs of 90% of U.S. drivers.

Lots of forces will bring an array of new electric cars to market in 2010 and 2011–technological improvements in batteries, concerns about climate change (despite legislative foot-dragging), worries about the U.S.’s dependence on imported oil and, most of all, the increasingly attractive economics around electric cars, which we’ll get to in a moment.

Having said that,  significant disagreements remain even among electric-car advocates about how fast the new technology will be adopted, and what form it will take. Will gas-electric hybrids like the Toyota Prius or Ford Fusion dominate, or will the market shift to plug-in hybrids like the Chevy Volt or all-electrics like the Leaf? Will electric cars be a niche business, a mainstream product or–maybe, just maybe–will they come to dominate? Or are they being overhyped? Certainly, there’s no shortage of skepticism out there, particularly from auto-industry incumbents.

“Yes, you will have the intellectual guys who drive electric vehicles,” scoffed Stefan Jacoby, CEO of Volkswagen Group of America, who spoke at the “green car” event. But, he argued, mass-market consumers won’t pay a premium for electric cars and they don’t want to deal with the hassle of charging their car batteries.

When Jason Wolf of Better Place opined that 50% of new car sales could be electric by 2020, Jacoby shot back: “That’s totally impossible. We need to be realistic.”

Still, Better Place has made more progress in the last couple of years–during a global economic meltdown–than most people would have expected. It’s got the support of the governments of Israel and Denmark for widespread rollouts, which require

Renault Fluence ZE

building charging stations as well as battery-switching operations throughout those two countries. (The Better Place model envisions battery switches for long trips.) It’s got a commitment from Renault build 100,000 electric cars, a new model known as the Fluence ZE (for zero emissions, a car that I wrote about here.) And yesterday’s round of Series B funding brings in new investors including HSBC, Morgan Stanley Investment Management, and Lazard Asset Management. Charles Stonehill, Better Place’s CFO, wrote on the company’s blog:

Our investors represent some of the largest financial institutions in the world, employing exceptionally thorough due diligence processes that are commensurate with the size of investment.

Given Renault’s commitment and the infusion of equity, don’t be surprised if the next country where Better Place rolls out its cars and its unique business model is France. Higher gasoline prices in Europe make Better Place a better business there.

Which brings us to the economics. While you’ll get arguments about the specific numbers, most people who have looked at electric cars will tell you that as battery costs come down, electric-powered engines are more efficient and less expensive to operate that gas-powered ones. Better Place’s Wolf says the cost per mile of fueling an electric car is two to three cents for the electricity, plus another five to six cents for the battery when amortized over the life of the car. Figure a dime a mile. In the U.S., with gasoline priced at $3, powering a car with gas costs 12-14 cents a mile. In Europe, where drivers pay $6 to $8 per gallon of gas, you can double that. The point is, there’s enough money to be made so that carmakers and consumers can both do well as electrics roll out, even though the upfront costs of an electric car are higher.

Not surprisingly, the start-up companies who are building only electric cars expect the technology to be embraced relatively quickly and widely. Established automakers, even those committed to electrics, are more cautious.

“We view this as a revolutionary journey,” said Nancy Gioia, director of global electrification at Ford Motor. Evolution might be more like it: By 2020, she said, Ford expects that between 10 and 25% of its new car sales will be electric. The bulk of those, she added, will be hybrids like the Fusion. With a hybrid, a gasoline engine can be used to overcome what the industry calls “range anxiety”–the driver’s worry that a battery could run out on long trips.

But Kevin Czinger, the dynamic CEO of CODA Automotive (who will be speaking at FORTUNE’s Brainstorm Green), proudly says that his company will be “100 percent independent of the oil industry.” CODA intends to start small, selling cars only in California beginning later this year, but Czinger is counting on market dynamics to both improve the product and drive sales.

“Do I think I can sell 1,000 high quality electric cars in California? Absolutely,” he said. That will signal markets that the business is real. “Do I know what the market will do with that signal? No. But market forces should work to drive down costs and drive up performance.”

He’s got a point. You never know what will happen with a disruptive technology comes along. When is the last time you bought a CD? Or a a new landline phone?

Says Czinger: “We envision an affordable electric car in every American garage.”