BMW 3 Series E46 M3 Convertible

The BMW M3 Convertible (E46) made its public debut in spring 2001. BMW records 29,633 cars and specifies the 3,246 cc S54B32 naturally aspirated inline-six, rated at 252 kW at 7,900 rpm, with a governed top speed of 250 km/h (155 mph). BMW's English archive pairs 252 kW with a 343 hp label; in UK imperial terms, 252 kW is about 338 bhp.

BMW's own archive pages conflict on the exact production months: one gives March 2001-November 2006, while another gives April 2000-August 2006 despite also saying the car was presented in January 2001. Contemporary and later BMW histories support a spring 2001 debut. The precise month boundaries are therefore left unresolved here rather than presenting one archive entry as settled.

Those numbers are the useful starting point, but they are not the whole buying story. An E46 M3 Convertible can have the conventional six-speed manual or the optional SMG II system; some early cars fall within BMW of North America's connecting-rod-bearing service-action window. On a car now old enough to have passed through several owners, build date, service records and evidence of work matter more than a classified advert's shorthand.

E46 M3 Convertible specifications

BMW's figures above are for the Convertible itself. That distinction matters because many E46 M3 specification tables mix coupe and convertible weights or acceleration figures without saying which body they describe. Where the source is not explicit, it is better to leave a number out than to give a precise-looking figure for the wrong car.

What makes the E46 M3 Convertible different?

The car shares the defining E46 M3 ingredients: the high-revving S54 six-cylinder engine, rear-wheel drive and M chassis hardware. BMW's archive also highlights the variable M differential lock, which could continuously develop a locking effect of up to 100 percent depending on the driving situation.

The obvious difference is the folding fabric roof, but that changes the used-car inspection as well as the driving experience. A Convertible adds roof motors, linkages, seals and drains to the list of things that must work properly. PistonHeads also notes Convertible-specific reinforcement around the rear of the car. On an inspection, a clean roof cycle and snug fit are useful evidence; hesitation, poor alignment or signs of water ingress deserve investigation rather than a quick assumption that the mechanism only needs adjustment.

Is SMG II an automatic?

Not in the conventional torque-converter sense.

The E46 M3's SMG II is an electrohydraulically operated sequential/manual transmission. PistonHeads describes it as using the same basic six-speed gearbox internals and clutch architecture as the manual, but without a clutch pedal: the hydraulic system operates the clutch and gear selection. BMW's own archive describes SMG II as optional and notes its automatic double-declutching on downshifts.

That explains why classified databases often label an SMG car automatic. The label is understandable from the driver's point of view because there is no clutch pedal and the system can perform shifts for you, but it is not a description of a conventional automatic gearbox.

For a buyer, the distinction is practical. On an SMG car, check the history for work to the hydraulic pump, relay, clutch and software, and make sure the system engages and shifts consistently when cold and hot. A seller calling the car automatic does not by itself prove what hardware is fitted; VIN/build information and the car itself should settle that question.

How many E46 M3 Convertibles were made?

BMW Group Classic gives a total of 29,633 M3 Convertibles.

That is preferable to estimating rarity from current adverts or combining coupe and convertible totals. It also makes the Convertible substantial enough to be its own production story rather than a tiny footnote to the coupe. Rarity within the total - by market, colour, transmission or option combination - needs separate evidence and should not be invented from how often a specification appears for sale today.

Rod bearings: use the build date, not just the registration year

There are two BMW service documents that are easy to blur together.

A March 2003 BMW of North America service-action Q&A described a narrower October 2001 to February 2002 production window. BMW of North America later issued SI B 11 04 04, dated December 2004, covering E46 M3 coupe and convertible cars with the S54B32 produced from 12 February 2001 through 22 May 2003.

The later bulletin says the connecting-rod bearings fitted to those cars were not manufactured to BMW quality standards and could overheat and fail when the engine was used at sustained higher speeds. Its remedy was replacement of the connecting-rod bearings plus updated engine-control-module programming.

For a North American car, the useful question is not simply Is this a 2002 or 2003 M3? It is:

1. What is the car's actual production date?
2. Does that date place it inside BMW's later service-action window?
3. If it does, is there documentary evidence that the action or equivalent bearing work was completed?
4. If later bearing work has been carried out, who did it, when, and with what parts?

A 2003 registration by itself does not answer any of those questions. A car could have been built on either side of the 22 May cutoff, and registration date does not prove that a campaign was completed. For a UK car, the North American bulletin is useful historical evidence but does not prove that the same action applied in Britain. Check the VIN, build record and BMW/dealer history; this review did not recover a primary UK campaign record.

What should you inspect before buying one?

A low odometer reading is useful context, but it does not replace age- and history-based checks.

Service history comes first. PistonHeads recommends confirming the original 1,200-mile running-in service, an important marker on an M3 history file. Check the chronology rather than accepting a stack of unrelated invoices as complete history.

Inspect the rear floor and rear axle carrier panel area. Cracking here is a recognised M3 inspection point. Specialist Redish Motorsport notes that an underside-only check can miss signs inside the cavities beneath the rear seat and boot floor. Evidence of reinforcement or repair is not automatically bad, but it should be understood: who carried it out, what was repaired, whether the surrounding structure was sound and whether the work is documented.

Treat SMG II as its own system. On an SMG-equipped car, investigate pump, relay and clutch history and test the gearbox through different temperatures and shift modes. A fault blamed on the expensive hydraulic pump can sometimes be something simpler, so diagnosis matters.

Check VANOS and engine history without reducing the car to one internet fear. The S54's variable camshaft system is another area where invoices, specialist inspection and symptoms are more useful than a generic claim that every car needs the same repair at the same mileage.

Operate the Convertible roof repeatedly. The fabric hood should move smoothly and sit correctly. Check linkages, seals, condition of the fabric and evidence of water ingress. PistonHeads specifically recommends regular lubrication of the folding-roof linkages.

Inspect age-related chassis items. Front ball joints, wishbone bushes, rear trailing-arm bushes, springs and dampers all deserve attention. On a car modified from factory specification, ask why the parts were changed and whether the geometry was set correctly afterwards.

A TMJC-linked 2003 example

A surviving Car & Classic syndication attributed to Matt Johnston / The Matt Johnston Collection records a 2003 BMW E46 M3 Cabriolet with 24,643 miles, right-hand drive, a six-speed transmission and the transmission category shown as Automatic.

That individual advert is useful here for one reason: it demonstrates the terminology problem. On an E46 M3, an aggregator's automatic category should prompt the reader to establish whether the car is SMG II rather than assume it has a conventional automatic gearbox.

The same restraint applies to the rest of the car. The syndication does not establish its exact build date, whether a market-specific BMW rod-bearing service action applied, whether that work was completed, or the originality of every current component. Those are individual-car questions for VIN/build data and the history file, not facts to infer from the model year or mileage.

What is worth preserving on an original car?

Originality is best assessed as a coherent record rather than a checklist of easily swapped parts. Start with VIN/build specification and period documentation, then compare the car's body, interior, wheels, transmission and equipment with that record. Service campaigns and sympathetic age-related repairs do not make a car less genuine; undocumented specification changes are a different question.

For a buyer choosing between a highly original car and a modified one, the useful distinction is not that all modification is bad. It is whether the changes are reversible, well engineered, documented and appropriate to what you want from the car.

The wider BMW 3 Series reference explains where E46 sits in the model line. A dedicated E46 generation reference is the natural next addition to this branch.

Sources and further reading

• BMW Group Classic - BMW M3 Convertible (E46)
• BMW Group Classic - BMW 3 Series Sedan (E46)
• BMW SI B 11 04 04 - connecting-rod-bearing Service Action, archived by Operation CHARM
• BMW SI B 11 04 02 - earlier S54 extended-warranty bulletin, archived by Operation CHARM
• PistonHeads - BMW M3 (E46) used buying guide

Additional verification sources:

• BMW Group Classic - alternate M3 Convertible archive record
• BMW Group - 30 Years M3 retrospective
• BMW of North America - March 2003 S54 service-action Q&A
• BMW of North America - SI B 11 04 04 mirror
• Redish Motorsport - E46 M3 RACP inspection