Sept. 5 (Bloomberg) -- Platinum rose for a third day in New York on signs of increased demand from automakers, the biggest users of the metal. Palladium for immediate delivery declined.

U.S. vehicle sales gained in August to an annual rate of 16.3 million units from 16.2 million a year earlier, U.S. research company Autodata Corp. said yesterday. Platinum has climbed 12 percent this year as accelerating U.S. economic growth spurred demand for cars and strikes disrupted supplies.

"The auto sales suggest the market is still strong and platinum prices will hold,'' said Helen Henton, head of commodity research at Standard Chartered Plc in London. ``If you do see a slowdown in U.S. growth, you would expect industrial use of platinum to suffer.''

Platinum futures for October delivery gained $2.10, or 0.2 percent, to $1,275.80 an ounce as of 8:19 a.m. in electronic trading on the New York Mercantile Exchange. Platinum for immediate delivery fell 75 cents, or 0.1 percent, to $1,274 in London.

Makers of emission-control devices for vehicles bought 62 percent of platinum produced last year, according to London-based metals trader Johnson Matthey Plc.

"Automobile sector demand is positive,'' said Peter Fertig, a consultant to Dresdner Kleinwort in Hainburg, Germany.

Spot palladium declined 50 cents to $331.

The 9:45 a.m. "fixing,'' the price used by some mining companies to sell production, rose $3 to $1,275 for platinum and increased $1 to $331 for palladium.