Less than a week after Tesla Motors revealed the first production model of its souped-up, all-electric sports car, the company already is talking about when customers can expect a glimpse of its next vehicle.

In the second quarter, Tesla will unveil the design for its family car, code-named "WhiteStar," said company Chairman Elon Musk on Wednesday at the Clean-Tech Investor Summit in Palm Springs, Calif.

Aside from its flashy two-seat Roadster, Tesla plans to make 20,000 to 30,000 per year of its next model, a four-door sedan.

The company also plans to offer consumers a choice of an all-electric WhiteStar sedan or a gas-electric hybrid version.

For some industry watchers, it might come as a surprise that Tesla, the beacon of electric-car possibilities, is putting gas into its vehicles. But the road to bring electric cars to the masses is riddled with major obstacles.

Among the roadblocks are batteries, which are key to getting better mileage out of vehicles that run only on electricity (see Batteries Key to Plugging in at Electric Vehicle Symposium).

So, is the act of Tesla building a gas-electric car an admission of the challenges of going all-electric?

No, Musk claims.

"I think it's important that people have a choice," he said, explaining that some people might prefer the range gasoline will add to the car.

But that's not to say Tesla isn't improving the allure of its all-electric WhiteStar model.

"We're also doing things that will help the range issue on the electric side, such as improving the charge time to under an hour," he said.

The company is also developing the WhiteStar's battery pack to be switched out quickly.

Musk said there is no firm date as to when the WhiteStar is expected to go into production. But if he had to guess, he said, it probably will be 2010. And the first model to go into production will be the all-electric version, he said.