Two California startup makers of luxury electric cars can thank Nissan Motor Co. and Honda Motor Co. for crowds they are drawing at Detroit's auto show.

Nissan skipped the show and the international media attention that goes with it and Honda canceled a briefing on models as U.S. auto sales reached a 16-year low. The spotlight then turned to Fisker Automotive Inc., which hasn't shipped its plug-in hybrid, and Tesla Motors Inc., the maker of only 147 battery-only Roadsters. Now the little-known car makers need to lure buyers.

Barriers to entering the industry have fallen, said John Casesa, a partner at consulting firm Casesa Shapiro Group. The business plans of Fisker and Tesla could work, but at these very low volumes it is extremely challenging to earn an adequate return on investment, he said.

Volatile fuel prices, tighter emissions rules and stronger batteries are buoying interest in cars that use little or no gasoline. Plug-in hybrid and battery-only cars may account for as much as 12 percent of U.S. vehicle sales by 2020, according to Munich-based consultant Roland Berger & Partners GmbH. While Tesla and Fisker are reaching the market first, they start vying next year with the first rechargeable models from Nissan, General Motors Corp., Toyota Motor Corp. and Ford Motor Co. and the startups need more funding.

That's going to be a huge challenge for them, continuing to raise money to add models and expand operations, said Aaron Bragman, a Troy-based analyst at IHS Global Insight.

Tesla plans to deliver 1,000 Roadsters this year. The car costs $109,000 and can travel as far as 244 miles on battery power. Next month, the San Carlos, Calif.-based company will display a second car, the $57,400 Model S sedan due in 2011, Chief Executive Officer Elon Musk, 37, said.

Tesla raised $187 million, including about $70 million from Musk, who co-founded Internet payment service PayPal and made about $300 million from public offerings of PayPal and software company Zip2 Corp.

Fisker, based in Irvine, Calif., this year plans to deliver 200 Karma sedans, designed by Chief Executive Officer Henrik Fisker, 45, and as many as 15,000 in 2010. The $87,900 Karma travels 50 miles on battery power before a gasoline engine engages to recharge lithium-ion packs.

Fisker's system, similar to GM's Volt, which goes on sale next year, may provide an average of 100 miles per gallon of gasoline, Fisker said.

Tesla is seeking $350 million in U.S. government loans to develop and build the Model S, and the company applied for $100 million in financing to make drive systems for other carmakers.

The company said Jan. 13 it will sell 1,000 battery packs for Daimler AG's electric Smart minicar, its first deal with a major automaker.

Fisker applied for the same low-interest federal loans sought by Tesla, part of a $25 billion advanced vehicle program run by the Energy Department. Henrik Fisker wouldn't say how much the company seeks.

While Fisker designed his car and has a drivetrain from partner Quantum Fuel Systems Technologies Worldwide Inc., he outsourced engineering and production work.

"You don't have this heavy drain on cash," Fisker said. "That gives you a whole new potential that wasn't available 20 or 30 years ago."

Tesla's Musk wants to keep design and engineering in-house for brand distinction.

"If everything is outsourced how do you build brand value?" Musk said.

Both companies have rushed to secure investors.

The reason many of the car startups fail fast is that they can't cover the immense investment of creating a car from the ground up, Casesa said. In many ways, Fisker is not creating a car from the ground up in the same way Tesla is.

It was a fortunate coincidence that Tesla decided to attend the North American International Auto Show just as rivals pulled out, said Rachel Konrad, a Tesla spokeswoman. "If this had been some other year and we'd signed up so late, we'd have been in the basement," Konrad said.