As it turns out, the rise of fuel economy doesn’t mean the end of the fun.

In an effort to keep up with the times (and by times I mean the regulators at the EPA,) BMW is for the first time since 1999 offering a car powered by four-cylinder engine in the United States.

The Z4 sDrive28i is a fitting ambassador for this olive branch of efficiency. The two-seat, retractable hardtop roadster is easily BMW’s sexiest car, and hard to say ‘no’ to, regardless of what’s under its swinging sixties-style elongated hood.

Here, you’ll find an all-new 2.0-liter turbocharged engine where only inline-sixes have lived since the model was introduced 2 years ago. It effectively takes the place of last year’s normally-aspirated 3.0-liter model, and may put it in its place, too.

Rated at 240 horsepower and 260 lb-ft of torque, it compares very favorably to the 255 hp and 220 lb-ft figures of the old engine. But it’s also lighter, which is an added (or is that subtracted?) bonus that pays benefits in the areas of acceleration and handling.

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Of course the folks at BMW weren’t thinking about such frivolous things when they created the sDrive28i, only doing right by Mother Nature (yea, right.) To that end, the car gets more than 20 percent better fuel efficiency than the outgoing model, which is amazing in an un-hyperbolic way.

Fuel economy jumps from 18 mpg city and 28 mpg highway to 22/34. Not that that a number like that last one really needs any perspective, but the 813-pound lighter, 73 hp less powerful Mazda Miata can manage only 28 mpg.

A slick, 6-speed manual transmission is standard and has throws shorter than the palm of your hand, but an 8-speed automatic is also available. For those of you not keeping track, that’s two gears for every cylinder.

Manual Z4s are also equipped with a stop/start system that turns off the motor when the car is stationary and lights it back up again when you engage the clutch. It’s a little rough by BMW standards when it does, not bad, but obviously worth mentioning. If you find it really annoying, you can deactivate it. I didn't.

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Off the line there’s just a notion of turbo lag before max torque hits at an extremely low 1250 rpm. From there it sings toward redline, literally. The combination of noises from the engine, gearbox and exhaust has the deep orchestral sound of a small heavy metal band fronted by the falsetto-voiced turbocharger.

Let of the gas to shift, and it lets out a satisfied gasp of air as the blow-off valve opens and a bit of unburnt fuel rumbles its way through the pipes. Best of all, you get all of this aural feedback even with the retractable hardtop closed. The Z4 is as refined, but not sterile. If there’s a better sounding four-cylinder car in the world, there isn’t.

Zero to 60 mph takes 5.5 seconds, but feels quicker than that. The chassis is stiff for a roadster and the ride supple, with just enough body roll to keep you from getting into trouble. This isn’t a track car, but you’ll appreciate that on mountain roads that can use a little TLC.

The Z4 is still available with turbocharged inline-six-cylinder engines of 300 and 335 hp, but the extra $6,00-$15,000 more that you’ll pay for them hardly seems worth it. Think of the money and fuel saved as an excuse to take the long way home.

Click here for a review of the Z4 sDrive35is

And get used to this engine because you’ll be seeing a lot more of it soon. While its date with the low-volume Z4 represents a drop in the bucket of imported oil, next year things get real when it becomes in the 3-Series and the 5-Series, big players both.

BMW’s headquarters building in Munich is shaped like four-cylinders. It’s nice to see that it didn’t forget how to make them work.


2012 BMW Z4 sDrive28i

Base Price: $49,525

Type: Rear-wheel-drive 2-seat roadster

Engine: 2.0-liter turbocharged 4-cylinder

Power: 240 hp, 260 lb-ft torque

Transmission: 6-speed manual

MPG: 22 city/34 hwy