* Two firms to add 500,000 tonnes/year autosheet capacity
* Deal will be finalised shortly - Kobe
* Competition for clean-car tech helps - fund manager (Adds comment on financing in 3rd paragraph)
By Yuko Inoue
TOKYO, Dec 1 (Reuters) - Japan's Kobe Steel Ltd is in the final stage of talks with U.S. Steel Corp to add a $480 million auto sheet steel line at their joint venture in Ohio, eyeing growing demand for lightweight steel used in fuel-efficient cars.
Japan's No.4 steelmaker said on Wednesday it and U.S. Steel are discussing boosting the production capacity of high-tensile automotive sheet at their 50-50 joint venture Pro-Tec Coating Co by 50 percent, by adding a line with capacity to produce 500,000 tonnes per year.
The total investment cost and other financial details are still being finalised, a Kobe spokesman said, denying a comment by a company source that it might shoulder the bulk of the 40 billion yen ($478.6 million) needed to build the line.
Kobe Steel is betting heavily on a recovery in the U.S. car market, anticipating strong growth in demand for fuel-efficient vehicles that use light but strong high-tensile sheet steel, as governments tighten environmental and fuel-economy standards.
"As carmakers compete for deeper cuts in emissions and bigger gains in fuel efficiency, demand for high-tensile sheet steel will grow," said Atsushi Osa, a fund manager at Toyota Asset Management.
"The high yen is also a strong tailwind," he said.
It would be the first such investment by a Japanese steelmaker in the U.S. steel sector in nearly 15 years.
The Nikkei business daily reported on Wednesday that construction of the new line would begin in 2011, with production starting in 2013.
Kobe, which aims to boost overseas sales to half its overall revenues, also agreed on Tuesday with Steel Authority of India Ltd to begin talks on joint production and other areas of cooperation.
Demand for high-tensile sheet steel, produced mostly by Japan's Nippon Steel Corp and JFE Holdings Inc and South Korea's POSCO, is expected to grow because it is used in electric cars and hybrids to improve fuel-efficiency.
Kobe is strong in the upscale products of high-tensile sheet.
General Motors Co, which returned to Wall Street this month with a $23 billion initial public offering, said it planned to hire 1,000 engineers and researchers over the next two years to develop more electric cars and hybrids as it launched its battery-powered Chevrolet Volt.
Toyota Motor Corp said it would launch 11 new hybrids and a rechargeable Prius that may cost as little as $36,000 as it pursues plans to stay in front in clean-car technology.
The U.S. car market is also slowly recovering. U.S. November auto sales held above 12 million vehicles on an annual basis, a gain of about 10 percent from a year earlier, driven by month-end discounts and a slow return in consumer demand, according to analysts.
Kobe's rival Nippon Steel, the world's fourth-biggest steelmaker, has an automotive sheet steel capacity in the U.S. jointly with ArcelorMittal of 1.7 million short tons (1.54 million tonnes) per year.
Shares of Kobe Steel were up 1.6 percent by late afternoon, while the benchmark Nikkei average was flat. ($1=83.57 Yen) (Editing by Michael Watson)