If you want to travel in style and comfort with an open blue sky above you, the 2015 BMW Z4 should be right up your alley. This luxury roadster has the performance, refinement and good looks we expect for this class of car, and it's certainly one of our favorites.

Starting things off for the Z4 is the entry-level sDrive28i. Its base four-cylinder engine will likely satisfy most drivers and returns good fuel economy for the class. For that classic BMW feel, though, you can't beat the sDrive35i with its smooth inline-6 engine and impressive acceleration. The Z4 is tuned to be more of a grand touring car than an outright sports car, but the result is sporty enough handling on back roads and a comfortable ride on the highway. Moreover, its power-folding hardtop is an engineering marvel, and it adds a pleasing dose of security compared to soft-top rivals.

Another Z4 advantage is that it's pretty practical given its relatively compact dimensions. The seats are roomy enough for 6-footers, and the trunk can easily accommodate a weekend getaway's worth of luggage (though the roof takes a bite out of that space when retracted). If you're dreaming of an idyllic road trip with plenty of sun and winding tarmac ahead of you, you can't do much better than this BMW.

Even though we like the Z4 quite a bit, its price tag can shoot up quickly with a few options added. Plus, there are other desirable alternatives in this rarefied class. The Porsche Boxster is a true athlete and offers a more engaging feel when driving through turns, while the Mercedes-Benz SLK-Class boasts top-shelf refinement and available V8 power. If you haven't driven a Chevrolet Corvette lately, its blend of performance and sophistication may surprise you. And if you just want a minimalist roadster experience, we always recommend the joyful Mazda MX-5 Miata. But all things considered, the 2015 BMW Z4 remains one of the most well-rounded luxury roadsters available and we definitely recommend a test-drive.

The 2015 BMW Z4 is a two-seat convertible with a retractable-hardtop roof. There are three versions that correspond to engine choice: sDrive28i, sDrive35i and sDrive35is.

The 28i comes standard with the four-cylinder engine, 17-inch wheels, automatic and adaptive bi-xenon headlights, LED running lights, automatic wipers, heated mirrors, keyless ignition and entry, cruise control, dual-zone automatic climate control, eight-way power seats with driver memory functions, a leather-wrapped tilt-and-telescoping steering wheel, leatherette premium vinyl upholstery, auto-dimming mirrors, basic BMW Assist service, Bluetooth phone and audio connectivity and a sound system that includes a CD player, HD radio, an auxiliary audio jack and an iPod/USB audio interface.

Besides its more powerful six-cylinder engine, the 35i gets 18-inch wheels, sport seats (with adjustable side bolsters and thigh support) and sun-reflective leather upholstery. If you aren't interested in the larger engine, these items are also available on the 28i.

The 35is adds an even more powerful engine, unique styling cues, a lowered suspension with adaptive dampers, an upgraded audio system, upgraded interior trim and a sport steering wheel.

There are several options packages available for all three trim levels. The Cold Weather package adds heated front seats, a heated steering wheel and retractable headlight washers. The M Sport package is standard on the 35is save for its 19-inch wheels and increased speed limiter, but on the other trims it adds the 35is's adaptive suspension, aerodynamic body kit, sport steering wheel and special interior trim (note that the 28i is limited here to 18-inch wheels). The Technology package features a navigation system, 12GB of music storage, voice controls, enhanced BMW Assist and smartphone apps integration. Color-themed packages are also available that feature leather seating, the power sport seats, a simulated suede headliner and various interior accents.

Available for the 28i is a Sport package (18-inch wheels, sport seats, adaptive suspension and increased top speed limiter). Both the 28i and 35i can be had with a Premium Sound package that includes the 35is's upgraded audio system along with satellite radio.

Stand-alone options include different wheels, front and rear parking sensors, automatic high beams, a heated steering wheel, heated seats and satellite radio.

The 2015 BMW Z4 sDrive28i features a 2.0-liter turbocharged four-cylinder making 240 horsepower and 260 pound-feet of torque. Rear-wheel drive is standard, and you can get either a six-speed manual or an eight-speed automatic at no extra cost. Manual-equipped cars include an automatic stop-start function that turns off the engine when the car is stopped to improve efficiency. In Edmunds performance testing, a manual-equipped Z4 28i went from zero to 60 mph in 5.8 seconds, similar to what the V6-powered Mercedes SLK350 runs. EPA-estimated fuel economy is 26 mpg combined (22 city/34 highway) with the manual, with a 1 mpg drop in highway mileage for the automatic.

The Z4 sDrive35i gets a 3.0-liter turbocharged six-cylinder that produces 300 hp and 300 lb-ft of torque. It's paired exclusively with a seven-speed automated manual transmission (known as DCT). BMW estimates that the Z4 will hit 60 mph in 5.0 seconds. EPA estimated mileage is 20 mpg combined (17 city/24 highway).

The Z4 sDrive35is gets a more powerful version of the 3.0-liter turbo-6 good for 335 hp and 332 lb-ft of torque. The DCT is the only available transmission. In Edmunds testing, the 35is went from zero to 60 in 5 seconds flat. Fuel economy ratings mirror those of the 35i at 20 mpg combined (17 city/24 highway).

Every BMW Z4 comes standard with antilock brakes, stability and traction control and side airbags. The antilock brakes integrate several features designed to improve braking performance -- one periodically wipes the brake rotors dry when the windshield wipers are in use, while another snugs the brake pads against the rotors if the driver abruptly lifts off the throttle. The BMW Assist eCall system is also standard and includes an emergency assistance button and automatic crash notification. This system can be upgraded to include BMW Assist Remote Services with features like stolen vehicle recovery and remote door unlock.

In Edmunds brake testing, the 28i came to a stop from 60 mph in an outstanding 103 feet. The other two models were essentially identical.

For some, a four-cylinder sports car at this price may seem less than ideal. The 28i's four-cylinder does clatter a bit at idle, and with the manual transmission, it comes with a fuel-saving engine stop-start feature that can cause intrusive shudders (at least BMW included a button to disable it). But if you hit the gas, we're pretty sure you won't have anything to complain about. This torque-rich engine pulls hard and has a pleasing exhaust note. The 28i also handles a bit better than its six-cylinder siblings thanks to its lighter weight.

Having said that, the 35i and 35is models are quicker, particularly at higher speeds -- and for some, the eerie smoothness of a BMW inline-6 is always worth the extra money. We'd approach the pricey 35is with caution, however, as its performance advantages over the 35i are minimal at best.

When the road gets twisty, the BMW Z4 doesn't feel as sharp as the Boxster, which remains the class favorite if you demand an engaging driving experience. Nonetheless, the Z4 is certainly no slouch around turns, especially with its adaptive sport suspension. At the same time, its relatively supple ride makes it an enticing substitute for the Mercedes-Benz SLK.

Inside the 2015 BMW Z4, you're greeted by a sleek dashboard, crisp analog gauges and consistently high-quality materials. It's an undeniably upscale environment. For a more custom feel, there are several two-tone color schemes that jazz things up a bit. Thoughtful touches include secondary knee-level air vents and a small cargo shelf behind the seats.

Despite its modest size, the Z4 is one of the more practical roadsters on the market. Legroom is typically at a premium in cars of this type, but the Z4 easily accommodates folks with longer inseams. Visibility is excellent even with the top up, thanks to large rear quarter windows that eliminate the blind spots typical in most roadsters.

With the roof raised, the trunk provides a generous 8 cubic feet of space. You'll lose some space when you lower the two-piece hardtop, but a fair amount remains, which is more than you can say for some other hardtop convertibles. There's also an available trunk pass-through that can accommodate longer items.