"Really? It's a wagon with an automatic transmission. It's only got 180 horsepower!" That's what the uninformed said when I raved about my time in the 2014 BMW 328d xDrive Sports Wagon. The car doesn't draw attention to itself and largely flew under the radar over the course of my testing.

But the diesel Sports Wagon has a secret -- when its torquey, unassuming engine combines with the optional M Sport upgrades and Dynamic Handling package, it becomes a rather good driver's car that balances comfort and efficiency with grin-inducing performance. This flexibility -- the ability to seamlessly tack a backroad blitz onto the end of your 40 mpg commute -- is hard to find and is what makes this particular BMW so special.

The diesel

Pop the hood with a double-pull of the release to reveal a 2.0 liter, 4-cylinder TwinPower Turbo Diesel engine that outputs 180 horsepower, 280 pound-feet of torque. This engine sounds and feels like what you'd expect a turbo diesel engine to; it's a little loud, a little rough, and is satisfyingly torquey.

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Power flows through an eight-speed sport automatic transmission that features paddle shifters, launch control, and wicked quick shifts when placed into its Sport program. As automatics go, this one is nearly as quick as a dual-clutch unit and is pretty smart about its gear selections. The tall 8th gear takes advantage of the diesel's low-end torque for exceptional fuel economy.

The 328d sports wagon is only available in the xDrive configuration, which indicates that its an all-wheel drive model.The torque split is 40:60, front-to-rear, but it can shift up to 100 percent of the grunt either way as necessary.

In addition to the Sport, Manual, and Normal settings for the transmission, the driver can select from Comfort, Eco Pro, and two Sport settings for rest of the vehicle. Comfort is the default mode, which optimizes the throttle and engine performance to their most balanced settings. Sport sharpens the throttle mapping for more responsive performance. Sport+ builds on that by loosening the stability control for more dynamic driving. Eco Pro adjusts the engine's performance and transmission shift program for better fuel economy while simultaneously adjusting the performance of the climate control system to further boost the miles per gallon.

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In all modes except Sport and Sport+, the BMW also utilizes an Auto Stop-Start system that shuts the engine down when stopped, for example at a traffic light, to reduce fuel wasted to idling. The diesel engine's restart is quick, but it's not smooth, coughing to life with noticeable effort. Drivers who find this bit annoying can disable the system with the touch of a dashboard button.

The EPA reckons the 328d xDrive Sports Wagon is good for 35 mpg combined, 31 mpg in the city, and 43 mpg on the highway. I averaged 41 mpg during my testing. My driving was pretty highway heavy with many miles spend cruising in Eco Pro mode with a few extended sessions of Sport+ mode corner carving when a particularly good back road opened up.

Now, 180 horsepower isn't an overwhelming amount of power; dropping down two gears for a pass with a quick double tap of the paddle shifter doesn't result in a neck-snapping bang of acceleration. Rather, the 280 pound-feet of torque comes on in a linear surge. This is a cruising engine and a very drivable one at that with a broad powerband. It feels just as strong when you're taking it easy as it does when you're flogging it.

The handling

Our example wasn't equipped with many options.

The first was a $1,000 Dynamic Handling package that adds an Adaptive M suspension and variable sport steering. The Adaptive M suspension features firmer components for a sportier ride, but both it and the variable steering are adjustable with the four drive modes. In Sport+ and Sport, the suspension and electric power steering firm up. In Comfort and Eco Pro, the ride softens up and the steering effort is lightened.

We also have a $3,850 M Sport package. This consists of styling upgrades, sport seats and an M Sport steering wheel, 18-inch wheels, and an Aerodynamic kit.

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In its sportiest settings, the sports wagon was surprisingly agile and an excellent driver's car. It stuck to the twisty corners of my favorite backroad even as I pushed far beyond the posted speed limit. The chassis stayed flat apex after apex and inspired great amounts of confidence.

What impressed me the most was how composed the wagon was during these high-speed hijinks. The diesel engine hums along at a low RPM thanks to its broad torque curve; the all-season tires don't squeal thanks to the xDrive system shifting power where the grip can be found; and the chassis feels comfortable and composed even when tucking into an apex. It's a good thing that the wagon form-factor doesn't attract a lot of attention to itself, because a car this comfortable at speed that could get you into a lot of trouble with the law if you're not careful.

The base level tech

Though the 3 Series is available with a wide range of optional infotainment tech, driver aid systems, and active and passive safety features, our example wasn't equipped with any of them.

The standard loadout is reasonably well equipped, but there are a few odd omissions and tech choices. For example, push-button start is a standard feature, but not smart keyless entry. So you have to get the remote transponder out of your pocket to unlock the doors as you approach, but put it back in your pocket to start the car with the ignition button.

Bluetooth is standard, which includes hands-free calling and text messaging, but I wasn't able to find Bluetooth audio streaming as an available source for the base 6.5-inch iDrive infotainment system. So if you're an Android, Windows Phone, or Blackberry user you'll need to either upgrade to a higher tech options package or deal with the 3.5mm analog auxiliary input and a cable to gain access to your favorite audio streaming app. (BMW's website states that the newer, but nearly identical 2015 model fixes this issue and features standard BT audio.)

iPhone users potentially don't fare much better. Though the BMW comes standard with a USB port, it requires a proprietary 30-pin adapter for iPod connectivity. If you're an iPhone 5, 5S, or 5C user, that means that you'd better bring your own lightning-to-30-pin adapter because that's the only way you'll get your tunes through the car's speakers.

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The bottom line

The 2014 BMW 328d xDrive Sports Wagon starts at $42,950. Our example wasn't much more expensive with the only additions to the bottom line being the M Sport and Dynamic handling packages and a $925 destination fee. As tested, this surprisingly capable wagon weighs in at $49,275.

For the money, the Bimmer is a flexible around-town vehicle with a good amount of space for people, pets, and cargo, an excellent road tripper that will effortlessly do 40+ mpg on the highway, and a pretty good drivers car when the road gets twisty.

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Though our example's loadout was pretty spartan, BMW does at least offer the tech that we like to see in a premium sports wagon... for a price. For about $950, you could add a rear camera and park distance sensors -- features that really should be standard at this price point. For $3,150, you can add navigation, a head-up display, and the BMW Online and BMW Apps as part of a Technology package. For $1,900, you can add lane departure warning, blind spot monitoring, and an around-view camera system. For $1,200, you can add adaptive cruise control and for $500 more there's an automatic parallel parking system available. There's premium audio, Xenon headlamps, and so many more options available.

It's pretty easy to end up with a car with significantly more amenities than our example, but you'll also be building a ride that's significantly more expensive.