Used 2008 BMW Z4 M Convertible

Combining muscle-car mentality with European sensibility, the 2008 BMW M is one of the most engaging sports cars under $55,000.

For Hitchcock, dialing "M" meant murder. BMW has been known to dial M as well. But in this case, any screaming you hear will be due to overloaded tires or passengers with wild eyes and death grips on the door handles.

The 2008 BMW M is a performance derivative of the Z4. Though its name is atypical -- cars rolling out of BMW's well-known M division typically have a number associated with them -- the M Coupe and Roadster are fully worthy of your attention.

The M Coupe or M Roadster (enthusiasts also call this car the "Z4M") have many performance-enhancing components from the previous-generation M3. It all starts with a 330-horsepower 3.2-liter inline-6. Smooth and high-revving, this is a BMW M engine in the most classical sense, especially as other M cars now have V8s or V10s. Contrasted with the Z4's optional 255-horsepower engine, the M's power plant delivers considerably more thrust to the rear wheels through an exclusive six-speed manual gearbox and limited-slip differential.

The M cars sport many other tweaks to the base Z4 as well, including a wider front track, a stronger rear subframe, hydraulic power steering for better feel (the Z4's is electric), 18-inch wheels and 225/45 front and 255/40 rear performance tires. The springs and dampers are sport-tuned, and the brakes are the same as those used for the old M3's Competition Package. Even the stability control system has been altered to be less intrusive.

Where the 2008 BMW M really shines, however, is when you get past mere specifications and slide behind the wheel. Owing to their light weight, sharp reflexes and aggressively quick acceleration, both coupe and convertible offer competent drivers a thrilling experience. With just two seats, a modest trunk and no automatic transmission, the M Coupe and Roadster are perfectly suited as go-fast weekend playthings.

If you're looking for a daily driver, however, there are other competitors that also offer up plenty of smiles and may serve you better. The Porsche Boxster S or Cayman S are more expensive, but they're also quintessential sports cars with more polished and balanced driving dynamics that are less likely to get you into trouble should your driving be a little overeager. Meanwhile, this year's notably improved Chevrolet Corvette is much more versatile and offers the visceral punch of 100 extra horsepower and far greater torque.

So there's the brawny Chevy on one end of the sports car spectrum and the nimble Porsches on the other. The BMW resides happily in the middle, combining muscle car-like attitude with Continental-style design and build quality. Sound appealing? All you need to do is dial M.

The 2008 BMW M sports car is available as a hatchback coupe or roadster with a power-operated soft convertible top. The M is distinguished from its lesser Z4 sibling through subtle but purposeful styling enhancements including a more aggressive front fascia with larger air inlets, a pair of "precision" ridges in its aluminum hood and a set of quad exhaust outlets flanking a rear air diffuser.

As a line-topping vehicle, the single-trim M includes many Z4 options as standard equipment. These include 18-inch wheels, xenon headlights, leather sport seats and a 10-speaker audio system with CD/MP3 player. If you want cruise control and elastic storage nets, though, be prepared to ante up for the optional Premium Package. With this package you'll also get auto-dimming mirrors, eight-way power seats with driver memory settings, BMW Assist, Bluetooth connectivity and a THX-certified premium audio system. Other options include higher-grade full interior leather trim, heated seats, wood or carbon and leather accents, and a navigation system.

The BMW M Coupe and Roadster feature a high-revving 3.2-liter inline six-cylinder engine that cranks out 330 hp and 262 pound-feet of torque. A six-speed manual transmission transfers its power through a special mechanical limited-slip rear differential, resulting in 0-60-mph sprints in 4.9 seconds. Fuel economy for 2008, should you care, is not particularly good even for this class of car, checking in at 15 mpg city and 22 mpg highway.

The M is equipped with antilock disc brakes with automatic brake disc drying, stability control, traction control, side-impact airbags and rollover protection for the roadster. In government crash testing, the companion BMW Z4 roadster and coupe both earned four out of five stars for front occupant protection during frontal impacts. The convertible also received a three-star rating for side-impact protection.

From the driver seat, the view over the M's elongated hood -- made necessary because of the also-lengthy straight-6 power plant resting underneath -- gives the impression you're sitting in what should be the backseat, directly ahead of the car's driving wheels. Which is essentially true, and entirely understandable given BMW's desire for evenly balanced weight distribution in one of its premier sports cars.

Once underway, the engine spins willingly to its 8,000-rpm redline and, considering its size, delivers a surprisingly broad torque band that hurtles the car forward at any speed. The car's sharp responses -- the quick steering, instantaneous throttle and direct brakes -- won't reward a casual driving style, however. Many drivers might find the ride quality harsh and the car's lack of stability to be unsettling when driving hard on broken pavement.

The 2008 BMW M's intimate two-place cockpit features a pair of aggressively bolstered sport seats, well-placed controls, a thick M-edition steering wheel and materials befitting a luxury brand. Gone, however, are the flashy color combinations of the preceding M Roadster and Coupe -- aside from available red leather, the inside is pure staid class. For those who appreciate as much info flowing to them at all times, a 9,000-rpm Motorsport-spec tachometer with a variable redline is standard, reaching a heady 8,000 rpm when the oil reaches operating temperature. The speedometer tops out at 180 mph, but the vehicle's actual maximum speed is electronically limited to 155 mph. The roadster's trunk capacity remains virtually unchanged at approximately 9 cubic feet when the top is lowered. The coupe's enclosed hatchback design is a bit more practical with just under 13 cubic feet of space, although some may find the fixed roof a somewhat claustrophobic environment. It's no worse than the Cayman, however.