Electric sportscar maker Tesla Motors, which has yet to book a profit, said its fourth quarter 2010 loss was US$51.4m compared with $34.9m the previous quarter as improved gross margin was offset by increased spending on research and development and expanded sales and marketing.

Q4 sales rose 16% to $36.3m and gross margin improved to 31% from 30%.

Full year sales of $116.7m compared with $111.9m in 2009 and gross margin improved to 26% from 9%.

Net loss for the year was $154.3m compared with $55.7m in the red for 2009.

Tesla CEO Elon Musk said: “Our powertrain team delivered solid results, with an increase in orders and record deliveries of battery packs and chargers for the Daimler Smart Fortwo electric drive, the completion of our development programme for the Daimler A-Class, and the commencement of the phase one development program for the Toyota RAV4 EV.”

Toyota took a $50m stake in Tesla last year and subsequently ploughed another $60m into the electric RAV4 programme.

Tesla said it remained on schedule for first deliveries of its Model S luxury sedan EV in mid-2012 which will be made at the former GM-Toyota Nummi factory in Fremont, California.

Installation of the manufacturing equipment continues on schedule, including "significant progress" with the installation of the hydraulic press line, the automaker said.

Tesla said it purchased over $17m of manufacturing equipment and spare parts from NUMMI and Toyota, "all of which was acquired at significant discounts compared to new equipment".

Tesla delivered its 1,500th Roadster during the fourth quarter and claims over 3,700 Model S 'reservations'.