The cars can get 40 miles per gallon in traffic and 50 on the highway, and they're not expensive hybrids nor do they need any special fuels, the Los Angeles Times reported Friday.
Ford Motor Co. said it will have a three-cylinder Focus or Fiesta for sale in the United States by the middle of next year.
"This engine is a game-changer," Steve Cropley of the British publication Autocar said of the three-cylinder Focus that just went on sale in Europe. "You barely hear the thing start, and it idles so smoothly you'd swear it had stalled."
Japanese makers Mitsubishi and Nissan and Germany's BMW and Volkswagen are all said to be working on three-cylinder designs.
Any vehicles with such small engines must be sure "not to compromise performance or fuel economy," to attract U.S. buyers, Rebecca Lindland, an analyst with IHS Automotive, said.
Manufacturers have been encouraged by how quickly Americans have been willing to move from large power plants down to four-cylinder models.
Forty-seven percent of the cars sold last year had four cylinders, auto survey company Edmunds.com said.
"Three cylinders shouldn't be much of a stretch," Dave Sullivan of automotive consulting firm AutoPacific Inc., said.