M3 So Sexy : BMW M3 Cabriolet (E46) [review]

Car Specifications
Engine: 
3246cc
Cylinder Layout: 
In-line 6, 24-valves, Dual VANOS
Top Speed: 
250 km/h (electronic limited)
Transmission: 
6-speed SMG
0-100km/h: 
5.5 sec
Power: 
343 bhp at 7900 rpm
Torque: 
365 Nm at 4900 rpm

It is true that open top cars have less structural rigidity than their coupe counterparts but in this case the E46 M3 Convertible has been strategically reinforced with some 70 kg more steel. Chassis shudder is minimal and only the worst roads revealed any sign of distress, it’s A-pillar remaining wobble-free for the most part. Mind you the suspension seems to be almost as firm as the coupe’s and the car came shod with ultra low profile 18-inch Pilot Sports mk1. (read the primer on M3 E46 HERE)

Whilst we would like to have said we enjoyed the pleasure of topless motoring it is truly a crazy thing to do in our equatorial noonday sun. What little we did sample served to show us just how impressively draft free the cabin was. With the side windows up, the front seats seemed just the place to be, even at triple digit speeds.

The main attraction of course is the M3’s engine but in this case it comes attached to BMW’s technically interesting SMG. While the SMG moniker will appear on mainstream BMW’s in future, it would stand for Sequential Manual Gearbox. The one in the M3 is the Motorsport version, beefed up and comes with six forward gears.

This latest version comes with two paddles not unlike Ferrari’s F1 transmission except unlike Ferrari’s, the SMG’s paddles are attached to the steering wheel like a proper F1 car. The only caveat is in a proper F1 car, the steering ratio is pretty much one-turn lock to lock and even with the M3's quicker ratio the steering needs to be rotated more than 360 degrees.

Ergonomically, the arrangement works well until one has to wind lots of lock onto the steering. Happily those circumstances are few and in most situations before entering a corner, proper driving technique would dictate that you have already engaged the correct gear for the corner and not choose to do it midway through. For a street going car, Ferrari’s arrangement might be a tad more logical.

However the SMG gives no quarter when it comes to it ability to deliver all the goods. There is no doubt, in full unbridled Sport/Race mode both these transmissions are sensational especially during track use but the SMG is far more user friendly when used in a less aggressive mode for everyday duties.

Of special mention must be the reverse selection that does not need the selection of neutral or a lifting of a switch to engage, one merely moves the floor mounted lever as if a traditional gearbox with a dogleg flick to the left. All very neat and instinctive.

Moreover the full-automatic mode tries to mimic a traditional torque-converter auto. This SMG has five levels of aggression, the first two levels are mild concentrating on slurring shifts and being unobtrusive.

The last two settings raise the abruptness of the change and does not try to shield you from the shift shock of transmitting all of the 343 bhp. The 3rd setting is a good compromise between the two extremes being sufficiently smooth yet offering appropriate kickdown response when it is called upon.

In the full manual mode, which by the way, is the raison de etre of the SMG, the sheer depth of the M3’s performance reserves can be tapped. Again there are five levels of SMG in manual shift mode. The first two are for the benefit of the passengers and the last two don’t bother with their feelings at all.

As with the auto mode the center position provides a good compromise between the two. It must be said, there is a last “hidden” mode that is available when one disarms the DSC. Selecting that allows you to get into the “Launch mode”.

It will do the same Ferrari party launch-trick of holding the revs up and aggressively engaging the clutch, lighting up the rear tyres on its way to a 5.5 second century sprint. It is not as spectacular as Ferrari’s flamboyant tyre smoking start but it gets the job done very efficiently with just a bit of wheelspin.

After disabling DSC, the hidden 6th LED bar on the dashboard indicating full “race or launch” mode can then be selected via the SMG button below the floor mounted lever. Sport mode should also be selected so the rest of the suspension and throttle response settings match. Push the gear lever forward and hold.

Floor the throttle and the revs rise to just over 4000 rpm. But watch your front before one releases the gearlever because the horizon will come rushing toward you in dramatic puff of expensive tyre smoke.

By holding the gearlever up, the car is braked electronically even with the throttle wide open. On its release, the brakes are released, the clutch engaged and the electronic throttle controls the openings of all six butterflies for a perfectly controlled launch.

Lest you get carried away, the manual says the clutch will only perform this twenty five times, so use sparingly. There is a memory that logs in the number of launches just in case you forget.

There are other useful everyday features designed to make life easier like the incline ascent assist. A tap on the left SMG pedal and the engine revs up just a little and the clutch is engaged halfway to allow some slip. This is useful in situations like carparks where the entry gantry or payment booth is on a slope. Again the number of times one can do this is limited because of clutch burn.

There is no doubt the SMG brings a whole gamut of useful functions but there isn’t one that a skillful driver cannot perform with a normal manual M3 except the auto mode. However this SMG is also a wonderful marketing tool.

The true blue enthusiast would probably choose the less complicated 6-speed manual but they are getting relatively rare nowadays and most well heeled clientele want some form of labour saving device like an automatic transmission in addition to the manual selection ability.

The only way to satisfy these buyers who insist on the best of both worlds is with the SMG. They can let their wives drive it occasionally without complaint and they can also enjoy it during track days. It might even be attractive to those who are accustomed to autos but still want a bit of manual fun.

But in either case, the heart of the matter is the superb M3 engine, one of the last high performance in-line six motors in existence today. It is highly tuned with 343 bhp from just 3.2-litres, easily crossing over the magic 100 bhp per litre threshold.

Not only does this engine has Dual VANOS operating its 24 valves, it has six individual throttle butterflies for each of the cylinders. These butterflies are servo operated which makes it easy to have proper traction control and many other various drive stability functions built in. It also makes it easier to have even more aggression in its throttle response once Sport mode is engaged.

There is no flat spot or hesitation from idle right up to the redline, just a smooth powerful surge of power throughout. So efficient is the engine in the mid-range it produces well over the 100 Nm per litre as well topping out at 365 Nm.

Compare these figures with many other normal aspirated engines and you will realize just how special this engine is, even among the ranks of just a handful of highly prized 100+ bhp per litre engines.

Handling is amazing for a convertible. It of course does not feel as razor sharp as the coupe but it cuts a formidable line amongst current open top sports cars. For most part, it remains in mild understeer mode so long as the DSC is armed. Selecting Sport mode stiffens up damping and heightens throttle response.

This is the position we selected for most of the trip despite the kidney-jarring ride for the passenger. Truth be told much as the steering has good feel, it is a trifle detached as far as the state-of-the-art goes. In sport mode, at least you recover some of that delicate sharpness.

With the guardian angel DSC in play, it is genuinely hard to get the M3 to perform any stunts. Turn it off and there is some fun to be had with the excess power the M3 has. It has enough grunt to make the M3 do doughnuts, albeit expensive tyre smoking ones.

Under or oversteer is now easily provoked revealing just how much the DSC is working behind the scenes saving one’s skin. Of course learning the envelop unfettered by electronic intervention is more of a genuine experience with the M3 and its capabilities but with such prodigious power it is just too easy to embarrass oneself.

There is hardly any weakness or criticism one can level at the M3 Convertible. It could do with a sexier body but that post is already filled up with some rather formidable machines. This niche pits it against the likes of the Jaguar XKR, Porsche 911 Cabrio, Maserati Spyder and the MB SL.

Admittedly it seems to be the junior upstart among such luminaries but it has the capability and race pedigree to stand up to the class contenders. In relative terms it also undercuts them by quite a margin but by mere mortal standards we are still talking big bucks here.

Fast Facts : BMW M3 Convertible SMG
ENGINE
CAPACITY : 3246cc
CYLINDER LAYOUT : In-Line 6
VALVES : 24, DOHC, Dual VANOS
BORE X STROKE : 87 x 91mm
COMPRESSION RATIO : 11.5:1
MAXIMUM POWER : 343 bhp at 7900 rpm
MAXIMUM TORQUE : 365 Nm at 4900 rpm

TRANSMISSION
TYPE : SMG(Sequential Motorsport Gearbox) 6-speed
DRIVEN WHEELS : Rear, Variable M Differential lock


PERFORMANCE
TOP SPEED : 250 km/h (electronically Limited)
0-100KM/H : 5.5 seconds

SUSPENSION
FRONT : MacPherson Struts
REAR : Independent central arm axle with double track control

BRAKES
FRONT : 328mm Ventilated disc
REAR : 325mm Ventilated disc

TYRES
TYPE : Michelin Pilot Sport
SIZE : F: 225/45 ZR 18, R: 255/40 ZR 18

SAFETY
ABS : Yes
AIRBAGS : Yes x 6
TRACTION CONTROL : DSC

MEASUREMENTS
LENGTH : 4492mm
WIDTH : 1780mm
HEIGHT : 1383mm
WHEELBASE : 2731mm
KERB WEIGHT : 1655kg
TURNING CIRCLE : 10.5m

PRICE IN 2002 : $356,000 without COE
WARRANTY : 3-year program
 

Summary
Whilst the M3 coupe has a clear roost of its own, the M3 Convertible is hemmed in by rather formidable foes. It has been granted entrance to this old boys club by sheer ability alone but for it to gain acceptance it must show its breeding. Being derived from the 3 Series stables is quite different from being purpose built like the rest. All told, its greatest draw is perhaps as the M3 Coupe’s alter ego, the wolf in a lounge suit. - AL
Photos: 
all content is intellectual property of motor-prime and cannot be reproduced in any form or manner without explicit permission from motor-prime. © 2004-2014 MotorPrime. All rights reserved.