We've been saying for a long time that one way carmakers will meet new, tougher gas-mileage rules is to make their engines smaller but more efficient.

Ford's EcoBoost lineup of direct-injected, turbocharged engines is one example, from a 3.5-liter V-6 used in full-sized pickups all the way down to a 1.0-liter, three-cylinder engine coming to the States in a couple of years.

Now Volkswagen is joining the fray as well.

A lengthy Car and Driver blog post on VW's new EA211 family of four-cylinder engines notes that the company may replace its base engine for U.S. Golf models--currently a 2.5-liter five-cylinder--with a turbocharged 1.4-liter four.

While peak power would fall slightly, to 140 horsepower from 170 hp, the torque of the default engine would actually rise to 184 from 177 pound-feet. And that torque is developed at a low 1400 rpm, meaning the engine needn't be revved hard for maximum thrust.

The hitch, according to the post, is that Volkswagen worries that even a small amount of turbo lag on a base engine would prove to be a customer turnoff.

2013 Volkswagen Jetta Hybrid

2013 Volkswagen Jetta Hybrid

But given VW's ambitions to boost its U.S. sales enormously, offering a full range of cars and crossovers, the company will have to get creative to stay within new EPA fuel economy rules as they tighten from the 2012 model year through to 2025.

We suspect that means the 1.4-liter turbo four will be widely seen across Volkswagen's compact car lines, both the Jetta and Golf. (As for the subcompact Polo, though, still no news at all....)

The 1.4-liter turbo four was first shown in the U.S. at last month's Detroit Auto Show, where it appeared in the 2013 Volkswagen Jetta Hybrid model that'll reach dealers this fall.

But the smaller engine will be offered as the base engine in the Jetta too, sans hybrid system.

Volkswagen is just the latest carmaker to offer a 1.4 turbo engine for maximum fuel efficiency. Chevy has one in the Cruze Eco, the 2013 Dodge Dart will have one as well, and we suspect more makers will follow.

It all goes to support the theory that 1.4 liters and 40 mpg highway are the new magic numbers for compact cars.


Follow GreenCarReports on Facebook and Twitter.