U.S. Steel Corp., the nation's biggest producer of the metal by volume, is making a comeback in debt markets as vehicle sales recover, fueling a surge in its bond prices from a record low.

The Pittsburgh-based steelmaker's benchmark debenture has climbed above 100 cents on the dollar, or par, for the first time since August after plunging to 87.75 cents on Oct. 5, the lowest since the debt was sold in March 2010. Credit-default swaps on the company are trading at an almost five-month low.

Auto production, which accounts for 24 percent of all steel shipped in the U.S., is at the highest levels since 2008 as carmakers respond to rising consumer confidence. At the same time, steel prices are up 15 percent since November as growth in the world's biggest economy eases stress from Europe's three- year debt crisis. U.S. Steel, America's first $1 billion company after its creation at the turn of the 20th century by Andrew Carnegie and J.P. Morgan, made at least 21 percent of its revenue the past three quarters from its European unit.