Roadsters used to be simple, impossibly tiny convertibles low in power but high in agility. Frills were few, but fun was abundant. They were also reasonably priced. With a lone exception, today's roadsters hardly fill this bill. The 2013 BMW Z4 and its two primary German competitors pack in the latest luxury features and power-retractable roofs. The Z4 has overwhelming power and isn't even that small. As for price? Well, we certainly wouldn't describe it as reasonable.

However, just because the Z4 represents a radical roadster shift doesn't mean that the fun has diminished. This BMW lives up to its brand's long-standing reputation for making supremely capable driving cars. The handling is excellent, the controls are engaging and each turbocharged engine -- either a relatively frugal four-cylinder or much stronger six-cylinder -- delivers strong performance.

Beyond its high-powered persona, the Z4's size and creature comforts provide something that those roadsters of yore definitely did not -- easy commuting and road trip livability. The Z4 has genuinely generous legroom, bettering not only its ancestors but its current competitors as well. Its features list is extensive -- slightly offsetting its eye-watering price -- while its power-retractable hardtop roof provides the cabin with an extra measure of serenity and security. Even the trunk is generously sized.

In total, the 2013 BMW Z4 is easy to love. While not possessing the perfectly balanced nature of the 2013 Porsche Boxster or the peerless refinement of the 2013 Mercedes-Benz SLK, the Z4 manages to strike a middle ground between the two. Yet we can't ignore the sky-high price tags attached to all three of these cars that frankly seem a little absurd. If you're looking for the modern embodiment of the classic roadster, the Mazda Miata is really your only bet.

The 2013 BMW Z4 is a two-seat convertible with a retractable hardtop roof. There are three models that correspond to engine size: sDrive28i, sDrive35i and sDrive35is.

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

Besides its bigger engine, the 35i gets 18-inch wheels, sport seats with adjustable bolsters and thigh support and sun-reflective leather upholstery. These items are optional on the 28i.

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

Each Z4 is eligible for the following optional packages. The Cold Weather package adds heated front seats, a heated steering wheel, extra storage items and retractable headlight washers. The M Sport package adds an adaptive M-tuned suspension, lightweight 18-inch wheels, an increased top speed limiter, an aerodynamic body kit, a thicker sport steering wheel and special interior trim.

Stand-alone options include different wheels, front and rear parking sensors, automatic high beams, steering wheel paddle shifters (automatic transmission only), heated seats, BMW Assist emergency communications, a six-CD changer, satellite radio, an upgraded sound system and the BMW Apps suite of smartphone-connected functions.

The 2013 BMW Z4 sDrive28i features a 2.0-liter turbocharged four-cylinder that produces 240 horsepower and 260 pound-feet of torque. Rear-wheel drive is standard and there is a no-cost transmission option of either a six-speed manual or an eight-speed automatic. 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, which is actually close to the V6-powered Mercedes SLK350. EPA-estimated fuel economy is 22 mpg city/34 mpg highway and 26 mpg combined with the manual, with the automatic losing only 1 mpg on the highway.

The Z4 sDrive35i gets a 3.0-liter turbocharged six-cylinder that produces 300 hp and 300 lb-ft of torque. It gets a standard six-speed manual (no auto stop-start), with a seven-speed automated manual transmission as a cost option (known as DCT). With the manual, the Z4 hit 60 mph in 5.2 seconds, which is quicker than the SLK and base Porsche Boxster. It ties the Boxster S. EPA mileage stands at 19/26/21 with the manual and 17/24/19 with DCT.

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. At full throttle, an overboost function increases torque to 369 lb-ft. The DCT is the only available transmission. In Edmunds testing, the 35is went from zero to 60 in 5 seconds flat. Its fuel economy is 17/24/19.

Every BMW Z4 comes standard with antilock brakes, stability and traction control and side airbags. The antilock brakes also integrate several features designed to improve braking performance, such as periodically wiping the brake rotors dry when the windshield wipers are in use and snugging the brake pads against the rotors if the driver abruptly lifts off the throttle. The optional BMW Assist emergency communications includes automatic crash notification, stolen vehicle recovery and on-demand roadside assistance.

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.

Some people might not like the idea of a sports car with a four-cylinder engine. Most won't like the sound of the 2013 BMW Z4 sDrive28i's four-cylinder at idle, as it produces an unbecoming rough clatter. But slot the manual transmission's slick shifter into 1st and lay into the throttle and we're pretty sure you won't have anything to complain about. This torque-rich engine pulls hard and has a sharp, warbling exhaust note reminiscent of BMW's past inline-6s. The 28i also handles a bit better than its six-cylinder siblings thanks to its lighter weight. The 35i and 35is are quicker, but truth be told, you'll be plenty happy with the 28i.

The Porsche Boxster remains the hands-down favorite when it comes to providing an engaging top-down driving experience. The Z4, especially with one of its sport packages, is certainly no slouch around corners, but its more comfortable ride, more spacious cabin and less communicative steering make it more of a grand touring car akin to the Mercedes-Benz SLK.

The 2013 BMW Z4's cabin is sleek and upscale. High-quality materials abound and combine with diverse shapes to create an undeniably premium environment. Several two-tone color choices add some further pizzazz, while additional standard features for 2013 are welcome given the Z4's elevated price. There are also a few thoughtful touches inside, including secondary knee-level air vents and a small cargo shelf behind the seats.

The Z4 is also arguably the most practical two-passenger sports car on the market. Legroom is plentiful, which is something you don't hear often about small convertibles. Visibility is also unmatched thanks to large rear quarter windows that eliminate the typical blind spots in most convertibles. With the hardtop roof raised, the trunk is quite large, measuring 8 cubic feet and capable of holding two sets of golf clubs and a carry-on suitcase. You'll have to ditch those clubs when you lower the two-piece hardtop, but the suitcase can remain, 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.