Here's the latest chapter in the ongoing BMW Z3 story: It's called the M Roadster. And it's real speed reading.
First there was the Z3. It's gorgeous, but with just 138 horsepower from its 1.9-liter inline 4-cylinder engine, it's a bit too tepid for serious sports car enthusiasts.
BMW followed up last year with the Z3 2.8. Its 189-horsepower inline 6-cylinder engine pretty much silenced the power pundits, but it was overshadowed by the new Porsche Boxster.
Now comes the M Roadster, with raw performance that makes the Boxster look just a bit tame. In the BMW alphabet, M stands for Motorsports. The engines and suspensions are developed in a separate skunkworks that's also home for BMW's racing activities. The Z3 is assembled exclusively at BMW's new facility at Spartanburg, South Carolina, and the M Roadster is the first M model BMW has ever assembled outside of Germany.
The M power in this case is BMW's familiar 3.2-liter dual overhead cam 24-valve inline-6 tuned to the high levels of the M3 coupe and convertible. The result is 240 horsepower and 236 pound-feet of torque. With a curb weight of 3,084 pounds, this adds up to impressive acceleration: 0-to-60 mph in less than 5.5 seconds, 0-to-100 in less the 14 seconds. The C5 Corvette is quicker, but not by a whole bunch.
The basic Z3 starts at $29,995, the 2.8 at $36,470, the M Roadster from $42,770.
Although the Z3 is basically unchanged for 1998, the aggressive tires and widened rear track that go with the M version lend an even more purposeful look to this car's classic good looks.
The M Roadster has a serious footprint to handle the extra thrust of its potent engine. That footprint also adds up to substantially higher cornering capabilities than the standard Z3, or even the Z3 2.8.
The essential difference between the 1.9-liter and 2.8-liter Z3 roadesters lies under that long, sculpted hood. The 2.8-liter engine is the same aluminum inline-6 used in the 328i coupe and sedan--twin overhead cams and four valves per cylinder. An inline-6 is still the best configuration for quelling primary vibrations--which is why BMW sticks with this design in an age of compact V6s. Both the 2.8- and 3.2-liter 6-cylinder engines are ultra-smooth at all operating speeds.
The 3.2-liter engine in the M Roadster generates great gobs of torque. Torque is really more important than horsepower, because torque is the low-down grunt that most of us use most of the time, whether we're making a stoplight launch or a fifth-gear pass on a two-lane highway. As you'd expect, the M Roadster is very good at sudden squirts of acceleration. Rowing up and down with the excellent 5-speed transmission--Getrag in regular Z3s, ZF in the M model--is part of the driving fun, but the engine's torque band is so broad that fourth and fifth gear can cover a wide range of urban and suburban driving.
A $975 four-speed automatic is available for the 1.9 and 2.8 engines, but the M version is manual only. The automatic operates in three modes--normal, sport, which raises shift points for better acceleration, and winter, which starts the car off in second gear to complement the traction control system (standard) in slippery going.
BMW did a good job of stuffing the extra pair of cylinders under the hood without making a significant change in weight distribution. Balanced at 52 percent front/48 percent rear, good weight distribution is a key element in the Z3's exceptional handling response.
On the downside, more engine means more mass--143 pounds for the 2.8, 361 pounds for the M Roadster. More engine also impacts fuel economy. The 1.9 is rated 23/31 mpg city/highway, the 2.8 is 19/27, the M version, for all its power, scores 20/27. More mass and more power require more stopping power, which the M Roadster supplies with big vented disc brakes all around.
A two-tone interior treatment distinguished the M version from the other two Z3s. Simplicity is a good thing and BMW got it right. Major controls are exactly where you'd expect them. Hop in, close your eyes and reach for something--the gearshift, for example. We'll bet your hand will make precise contact first time, every time--something we cannot say about all cars.
