Sales of automobile parts, including paint and plastics, helped DuPont post a better-than-expected quarterly profit, and a lower tax rate led the company to boost its 2011 forecast.

It's another positive sign for the broader economy and the company, which is transforming from a stodgy chemical maker to a diverse producer of products ranging from genetically modified seeds to stain-resistant carpet and Kevlar bullet-proof vests.

Earlier this month, DuPont said it would further expand into food by buying Denmark-based food additives maker Danisco for $5.8 billion cash.

For the fourth quarter, DuPont reported net income of $376 million, or 40 cents per share, compared with $441 million, or 48 cents per share, a year earlier.

Higher raw material costs, including a 20 percent jump in cost of goods sold, dented profit.

Excluding charges for job cuts and other items, DuPont earned 50 cents per share. By that measure, analysts expected earnings of 32 cents per share, according to Thomson Reuters I/B/E/S.

Revenue rose 15 percent to $7.4 billion. Analysts expected $6.95 billion.

Revenue in DuPont's performance chemicals unit, which sells titanium dioxide paint to car makers, rose 26 percent. Ford Motor Co is one of DuPont's biggest customers.

The performance materials unit, which makes plastics for automakers to cut down on the amount of metal they use, saw sales jump 11 percent.

DuPont also raised its 2011 earnings forecast to a range of $3.45 to $3.75 per share. It previously forecast $3.30 to $3.60 per share, and Wall Street expects $3.11 per share. The update was due in part to a lower tax rate, brought on by a tax agreement between U.S. President Barack Obama and Congress.

Shares of the Wilmington, Delaware-based company rose 21cents to $49.10 in premarket trading.

(Reporting by Ernest Scheyder; Editing by Lisa Von Ahn and Derek Caney)