This is the car BMW said it wouldn't build. When the Z4 was launched just over three years ago, the company insisted it had no plans to make either a four-cylinder version or an M model. Guess what? Both are in production today.

This turn of events is hardly surprising, though. With the latest Porsche Boxster S packing a 280bhp punch and Mercedes-Benz having shoehorned a 360bhp 5.4-litre V8 under the bonnet of its SLK, BMW was in danger of getting left behind in the power stakes. But it has responded, and in some style too.

While the four-cylinder Z4 2.0i was launched in some overseas markets last year, BMW waited till now to introduce the Z4 M together with a mid-life facelift for the entire range.

All Z4s benefit from design changes including new front and rear lamp clusters (the latter now have two-stage brake lamps that warn others when you make a panic stop), restyled bumpers and upgraded interior trim. Not huge differences, but the more angular front bumper does give a much sharper edge to the car's previously droopy nose.

Telling the weapons-grade Z4 M apart from the standard car is easy enough. A distinct 'power bulge' rises from the hood, there's a set of lovely 18-inch wheels and the front fog lamps have been ditched so the lower air intakes could be made as large as possible. Of course, it also has four exhaust pipes-BMW's M-car signature.

DRIVING IT

There are a few things a true motoring enthusiast should experience at least once in his life, and driving a car fitted with the Z4 M's 343bhp 3.2-litre six-cylinder engine ranks right up there with piloting a Formula One car and lapping the Nurburgring-Nordschleife race circuit in Germany.

This powerplant (shared with the M3) is outstanding in every respect-cultured at idle and well-mannered at low revs so the car is happy to pootle around town all day, yet possessed of a knockout punch at the top end.

Floor the throttle at any speed and the engine pulls like a train right up to 6,000rpm. Just when you start wondering if it might be a good time to grab the next gear, it finds a second wind that lasts all the way to 8,000rpm, and which is almost strong enough to knock your head backwards into the rollover hoops.

In a roadster with a specially-tuned exhaust system, this is all delivered with an accompanying soundtrack so brilliant you wonder why BMW even bothered fitting a radio. It's such an intense experience that the Z4 M really ought to have one of those 'Consult your doctor before use' labels stuck on its steering wheel.

The steering itself has hydraulic power assistance instead of the electric set-up on lower-powered Z4s, but while it feels crisp and responsive, true road feel is lacking. It's not that you'll have any problems aiming the car's nose accurately on twisty roads though, and sitting so far back in the chassis does help you feel what the rear wheels are up to.

And as long as the excellent DSC stability control system is armed, they'll be faithfully following the front axle, with even clumsy throttle applications in slippery corners failing to cause so much as a wiggle from the car's back end.

It's a different story with DSC offline, though. Smoky wheel-spinning starts and dramatic tail slides are there for the taking, but the use of the M3's high-tech rear differential means the car responds faithfully to throttle and steering inputs even when it's pushed beyond its grip limits.

INSIDE IT

Settle into the low-mounted seats and you'll notice how little has changed compared to the pre-facelift Z4. The dashboard is still an object lesson in stylish minimalism, and on the M it's covered with a huge swath of carbon-fibre-like trim.

Serving as reminders that this is no ordinary Z4 are M logos on the door sills, seats, steering wheel and illuminated gear knob.

DOLLARS AND SENSE

While exact pricing hasn't been announced, the Z4 M costs slightly more than an M3 Coupe overseas so expect a list price in the $340K region when the car is launched here in the second half of this year.

On the surface, you're paying more for less in terms of number of seats, boot space, equipment and so on. What you gain with the lighter Z4 M are serious bragging rights-BMW says the car laps the Nurburgring in eight minutes 15 seconds, a full seven seconds quicker than the already blistering time set by the M3.

VERDICT

The Z4 M's high-strung nature and uncompromisingly sporty character mean that it's not for everyone, but those who can appreciate its charms won't find a more ideal companion.

On the right roads, it gives an real adrenaline rush without the nagging element of fear, and none of its German rivals can match it in terms of performance per dollar. The Z4 M may be raw, but it's also very well done.

NEED TO KNOW

Model BMW Z4 M Roadster
Engine Type 3,246cc, 24V in-line 6
Maximum power 343bhp at 7,900rpm
Maximum torque 365Nm at 4,900rpm
Gearbox 6-speed manual
Top speed 250km/h
0-100km/h 5.0 seconds
Price To be announced
Warranty To be announced
Contact Performance Motors, 6319-0100

SIMILAR CARS WE HAVE DRIVEN

Mercedes-Benz SLK 55 AMG $368,888 with COE
Folding metal roof and automatic transmission mean the hottest SLK is an easy car to live with. 360bhp V8 makes a glorious noise but the chassis sometimes struggles to cope with all that power.


Porsche Boxster S $279,888 with COE
Now outgunned by its rivals in terms of raw firepower, but the mid-engined Boxster S still leads the way in terms of balance and steering precision in corners. It's not too expensive, either.