This downsizing is happening globally,” said Eric Fedewa, an auto industry analyst with IHS Automotive. “Sixes are replacing eights, fours are replacing sixes and now threes are replacing fours.”

Engines will only get smaller as automakers scramble to hit corporate average fuel economy standards expected to reach 54.5 mpg by the 2025 model year. ... adoption of turbocharging, direct injection, variable cam timing and other tricks ensures decent, if not stellar, oomph. Ford, for example, boasts that its little three-cylinder will perform like a 1.6-liter four.

The trend is becoming common in midsized sedans, which traditionally have featured V6 engines. ... But we’re also seeing it in trucks. Ford says roughly 57 percent of the F-150 pickups sold during each of the past four months had V6 engines. ...

The bottom line, analysts say, is consumers are increasingly concerned with fuel economy and driveability, not the size of the engine. If a smaller engine provides better fuel economy and performance on par with a larger one, they’ll buy it.

“It used to be all about horsepower,” said Mike Omotoso, an analyst with J.D. Power and Associates. “Now it’s all about fuel economy. This downsizing offers the best of both worlds — it offers similar performance to a larger engine and improved fuel economy.”...

Three-cylinder engines will become increasingly common in Europe — where gas costs the equivalent of $8 or more a gallon — and Asia, but it remains to be seen whether we’ll see them here in the United States.