Lean and Mean Four-Cylinder Engines

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Four-cylinder engines have long occupied a place of low esteem in America, toiling beneath the hoods of budget sedans, compact trucks, and the occasional high-strung sports car. Most machines with aspirations of spaciousness or luxury require six cylinders or more. The last time BMW offered a four in the U.S., Wesley Snipes was still paying his taxes.

And yet a nice turbo four-cylinder can make such sense. In designing a car, very rarely do you get something for nothing – like, say, adding power, dropping weight, and improving fuel economy all at once – but that’s the promise of these new engines. Using combinations of tech trickery – variable valve timing, direct injection, transmissions with eight speeds or more – the new crop of turbo fours strives to smoothly churn out the power of six cylinders with the thriftiness of four. And for the most part, they succeed.

That’s why Americans can now find a four-cylinder in an Audi A6, a BMW 5 Series, and a Mercedes C-Class. Ford is putting a turbo four into its Taurus, Edge, and even the Explorer, while Range Rover is dropping that same motor into the Evoque. The Chevy Malibu and Hyundai Sonata banished their V-6s in favor of turbo fours. Even Cadillac is rolling out a four-cylinder ATS this summer. Its 2.0-liter makes 270 horsepower – about three times as much as its last four-cylinder, which appeared in the misbegotten Cimarron.

So why the craze for downsizing under the hood? Well, fuel economy is a concern even for people who are dropping $50,000 on a luxury car. And the (pictured, above) BMW 528i‘s 34 mpg on the highway demonstrates that Bavarian amenities and parsimonious efficiency don’t have to be incompatible. The Audi A6 2.0 – big, posh, does 0-60 in 7.5 seconds – gets 28 mpg combined, which is better than a Toyota Corolla 10 years ago.

But efficiency alone isn’t enough to tempt most American drivers. We require refinement, power, and the sense that we’re always moving ahead.

The scrappy 1.8-liter in the Mercedes C250 churns out more torque than the old V-6. And when I questioned whether 240 horsepower is enough for an Explorer, a Ford rep replied, “Hey, it wasn’t long ago you didn’t get that much power from an Explorer V-8.”

The Edge, a size smaller than the Explorer, does just fine with its EcoBoost propulsion, which actually makes more torque than its standard V-6. The only issue is that Ford charges $995 for the option. I’m no consumer psychologist, but I suspect that a significant number of car shoppers might balk at paying an extra grand for 45 fewer horsepower, fuel economy notwithstanding.

BMW takes the opposite tack with its new pint-size engine, quietly making the four-cylinder the default choice. When owners trade in their old six-cylinder 328i for the new model, I don’t suspect they’ll complain.

Right off idle, the turbo belts out enough boost to punch you back in your seat with a level of torque once exclusive to big sixes. Taking two cylinders off the front end helps the car’s weight distribution and thus handling. It’s clear BMW worked hard to ensure a motor with two-thirds the cylinders remains worthy of the spinning-propeller badge.

Our American automotive DNA is predisposed to celebrate the stuffing of huge engines into small cars. This year we learn to love the opposite approach. If you’re still leery about four-cylinders, go floor the throttle on a 528i. I think you’ll get over it.

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