A new generation of steel pistons is gaining favor in diesel passenger vehicles in Europe -- a strategic win in the lightweighting contest among steel, aluminum and other materials.
Steel pistons are common in medium- and heavy-truck engines in the U.S. and other global markets.
"In Europe it's a big thing. High-speed passenger-car diesels are going in this direction," said Joachim Wagenblast, director of product development for supplier Mahle Engine Components USA in Farmington Hills, Michigan.
He said some automakers have steel pistons "in the development phase" for U.S. diesels, but he declined to identify them.
Mahle has made steel pistons for Renault's 1.5- and 1.6-liter car diesels since 2014.
The pistons offer 3 to 5 percent lower emissions and correspondingly better fuel economy than traditional pistons, according to Mahle and Rheinmetall Automotive, another supplier that makes steel pistons through its subsidiary, KS Kolbenschmidt.