Harman International Industries Inc. (HAR) rose the most in four months after the maker of car audio systems reported third-quarter profit that exceeded analysts’ estimates and announced a record $2 billion contract.

The shares (HAR) gained 4.9 percent to $49.58 at the close in New York for their biggest daily increase since Dec. 20. They have advanced 30 percent this year after falling 18 percent during all of 2011.

Harman posted quarterly profit of 74 cents a share excluding a tax-related gain and costs for restructuring, beating the 67-cent average of three estimates compiled by Bloomberg. The contract is from a “luxury European automaker” for systems that provide in-car information and entertainment, Chief Executive Officer Dinesh Paliwal said in an interview, without identifying that company.

The value to Stamford, Connecticut-based Harman may exceed $3 billion as more consumers add in-dash navigation systems and equipment to link smartphones with vehicles, Paliwal said.

Net income in the quarter that ended March 31 more than quadrupled to $172.7 million, or $2.38 a share, from $36.6 million, or 51 cents, a year earlier, Harman said. Revenue rose 16 percent to $1.1 billion, helped by a 15 percent gain in sales of so-called infotainment systems, which connect vehicles to the Internet.

To contact the reporter on this story: Mark Clothier in Southfield, Michigan, at mclothier@bloomberg.net

To contact the editor responsible for this story: Jamie Butters at jbutters@bloomberg.net