Four-cylinder engines, often equipped with turbochargers, are very much in vogue at the moment.

It's unlikely to change any time soon, either, with Ford predicting that two thirds of U.S. vehicle sales will comprise smaller-capacity four-cylinder units by 2020.

That figure represents a fast climb from 40 percent in 2008, and 53 percent today according to The Detroit News. But tightening fuel efficiency standards will make smaller four-pots a necessity, rather than an alternative.

Car buyers themselves are already flocking to the raft of four-cylinder models available from various automakers.

Previously thought of solely as gas-saving models, recent technological developments, including direct injection and light-pressure turbocharging, have made them not just efficient but powerful too--comfortably replacing the performance that many would previously have turned to a V-6 or even V-8 engine for.

Some analysts suspect Ford's predictions are a little high, though Bill Visnic from Edmunds says it isn't implausible--"If you look at where things have been going segment by segment, except pickups, you could say that's been the trend."

Even those pickups have been downsizing over the last few years, with Ford once again at the forefront with its V-6 Ecoboost models drafted in as an alternative to the V-8s.

Elsewhere, four-cylinders are now the norm in everything from the minicar and subcompact classes right through to midsize cars and small SUVs. Companies like Ford, Hyundai and Mazda have all dropped V-6 engines from all but the largest or sportiest models.

In the smaller classes particularly, it might not even be long before smaller three-cylinder engines are commonplace--the impending Mitsubishi Mirage uses a 1.2-liter, 3-pot unit, and Ford is bringing its 3-cylinder Ecoboost to the U.S. under the nose of the Fiesta--it's great fun, as well as fuel-sipping.

While four-cylinder hybrids and four-cylinder diesels still dominate in terms of efficiency, there's still some debate over just how frugal the new generation of smaller turbocharged engines are in real-world driving, even compared to their larger counterparts.

That's hopefully something that will improve in time, particularly as carmakers find ways to bring down vehicle weight, better matching the engines' output and a car's bulk.

Modern four-cylinder engines also cost more than you'd expect, thanks to all that technology--so don't expect sticker prices to fall too much either.

But in general, new four-cylinders produce the same (or greater) power than previous V-6 units, are far smoother than they ever used to be, and offer up oodles of torque. And driven a little more gently, they've the potential to be far more economical too.

The conclusion? Small four-cylinder engines are definitely here to stay.


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