LOS ANGELES (Bloomberg) -- Tesla Motors Inc.'s fourth-quarter net loss widened to $81.5 million, as electric Roadster sales end ahead of the release of Model S sedans.
The company posted a fourth-quarter loss of $51.4 million in 2010.
Tesla is selling the final units of its $109,000 Roadster sports car.
The Model S, intended to expand the company's sales volume with a base model priced at $57,400, won't go into production until the middle of this year.
Until then, Tesla's main revenue source is supplying battery packs and other parts to Toyota Motor Corp. and Daimler AG, two of its investors.
The company also said today it's starting "a development program with Daimler for a new Mercedes-Benz vehicle with a full Tesla powertrain. This represents an increase in the scope and scale of our deepening relationship with Daimler," Tesla said, without elaborating.
Tesla said on Nov. 2, when it released third-quarter results, that it had a letter of intent from Daimler for the new vehicle project, but provided no details.
"My gut impression it's probably not something that will be for a mass-scale vehicle," said Ed Kim, industry analyst for researcher AutoPacific Inc. in Tustin, Calif.
While Tesla's projects with Daimler and Toyota aren't large in vehicle volume, "the benefit they get from even associating themselves with Daimler and Toyota is worth a ton," he said.
Han Tjan, a Daimler spokesman based in New York, wasn't immediately able to comment on the matter.
Tesla reported that fourth-quarter revenue rose 8.5 percent to $39.4 million and that annual sales increased 75 percent to $204.2 million.
For all of 2011, the electric car maker's loss widened to $254 million from $154 million in 2010.
Full-year revenue for 2012 may be as much as $600 million, with 90 percent of that coming in the second half, following the start of Model S sales, the company said.
Sales of Roadsters exceeded 2,150 through the end of 2011, and a final 330 units of the car will be sold in Asia and Europe this year, Tesla said.
Chassis production for the car at Group Lotus Plc's Hethel, U.K., factory has ended.
Tesla hopes to become a dominant seller of premium electric vehicles, aided by the agreements with Daimler and Toyota.
The company last week unveiled and began taking reservations for the Model X battery-powered SUV that goes on sale in 2013.
Tesla plans to build as many as 20,000 units of the Model S next year.
The company has said it expects Model S sales to help it become profitable for the first time by as early as 2013.
Advance sales of the Model X exceed 500 vehicles, representing future revenue of more than $40 million, Tesla said in a statement on Tuesday.
"This is by far the best-selling car in Tesla history, by a significant margin," Tesla CEO Elon Musk said Wednesday during a conference call.
The Model X, Tesla's first crossover, is derived from the underpinnings of the Model S.
The mid-size SUV, touted by Tesla as faster than Porsche AG's 911 sports car and roomier than the Audi Q7 SUV, will be built in 2013 at the Fremont, Calif., plant that starts making the Model S this year.
Model S reservations exceed 8,000, the company said on Wednesday.