E46 Home

Models

Interior

Options

Tourings

Convertibles

Compacts

Gallery

Mechanics

Problems

//M Car

Tuners

 

BMW E46 Three Series - M3

Background

The arrival of a new M3 is always eagerly awaited and for the E46 it came at the end of 2000. The E46 M3 was not to disappoint the faithful, unless they wanted a four door saloon or touring. The car was available only as a coupe or convertible this time.

 

BMW E46 M3

M3 in Phoenix yellow, a very popular colour in the UK.

The S50 engine had been reborn as the S54, it now made 343bhp (22 more). In the USA the E36 M3 had been sold with a 3.0 version of the M52, a single throttle body engine. Although a superb unit (I saw one on a euro delivery car here in Scotland) it wasn't the full //M design. The E46 //M3 rectified this and was sold with the S54 in all markets. Critics praised it in all departments, in particular it handled a little better than the E36 M3.

 

BMW E46 M3 S54

The S54. The thing dreams are made of. Perfect.

In many ways the new M3 was a kind of E36 M3 Super Evo. The E46 was a little bigger and heavier but BMW engineers struggled to ring much more power out of the 3.2 litre six so the new S54 really had to push the limits. An engine is basically an air pump and the higher it revs the more power it makes so long as the fuel and air supply can keep up. The new engine made it's peak power 500 rpm higher up the rev range at a heady 7900rpm Peak torque was at 4900rpm compared to 3250 for the E36 M3 Evo 3.2.

A six speed Getrag gearbox was standard but much fanfare accompanied the new SMG II gearbox (see below). This was the second version of the SMG and allowed the driver to select the speed (or harshness!) of the gear change. It provided power to a differential of a unique design that sat in it's own custom subframe. As a result the M3's rear anti-roll bar wouldn't fit a normal E46 (a common E36 upgrade I did on my own car).

 

BMW E46 M3

2002 M3 in lustrous black.

The new Variable M Differential Lock system worked in conjunction with the M3's specially programmed DSC (dynamic stability control) to put down the power when things got slippery. It sensed the speed difference between the rear wheels and increased the pressure in an integrated shear pump. This activated a multi-plate clutch via a piston, and conveyed drive to the wheel with better grip proportional to the difference in wheel speed. In extremes all drive could go to the wheel with more grip. Once the slipping wheel regained grip pump pressure was reduced and the locking action decreased. Clever.

 

BMW E46 M3

Quad exhaust and bumpers without rubbing strips identify an M3.

To stop the monster BMW installed 325mm front and 328mm rear discs, all vented. As was the case with the E36 M3 the calipers were all single piston although there are a multitude of four pot upgrades available. ABS was standard.

Visually the new car had beefed up rear wheel arches done in a subtle yet powerful way. The bonnet had a large centre power bulge and of course there were the //M door mirrors. The front wings had extensions similar to the rear arches and a four slatted grille of their own with the //M badge displayed proudly. To accommodate the side grille the indicator repeaters were moved into the rubbing strips. From the rear the car's distinctive four exhaust tips gave the clue to its identity along with a more subtle boot lip spoiler. The bumpers were colour coded without the black rubbing strip inserts found on other E46s.

 

BMW E46 M3

Rev counter lit up on a cold engine.

Inside the seats lost the Vader wrap round headrests of the E36 M3 but still had a unique seat design, albeit a more subtle one. A Sport button in the centre console adjusted the throttle response but didn't increase power, not quite an //M button yet. In a bid to encourage drivers to reign in their enthusiasm and protect cold engines the rev counter had orange and red coloured lights which went out as the oil warmed up. As was previously the case (except on US M3s) the economy gauge was replaced with an oil temperature readout centered on 100C.

 

BMW E46 M3 CSL

M3 CSL with distinctive air intake hole in bumper.

M3 CSL

In 2004 BMW introduced a UK/euro special lightweight M3 CSL with 110kg weight saving. 1400 examples were produced in silver and black. The car had larger front brakes at 345x28mm but they were still single piston and the rear discs were unchanged 328x20mm. A slightly faster steering rack was fitted to sharpen things up. The suspension was upgraded to support the 17bhp power increase and a slight rise in torque. Engine modifications included high lift cams, reshaped exhaust headers and valves all fed by a carbon fibre lovers dream of an airbox.

 

BMW E46 M3 CSL

The CSL's gorgeous carbon fibre airbox.

Weight savings came from a reduction in sound deadening material, the use of lightweight manual seats, removal of the aircon, stereo and satnav. The latter were available as options to add a modicum of refinement. Some body and interior parts were made from carbon fibre including the centre console and roof. The glass was thinner too, you'd be amazed how heavy all the glass is in a car.

 

BMW E46 CSL

CSL lightweight seats and carbon interior panels.

Subtle external modification included carbon front splitters that improved down force at speed by up to 50% and a carbon rear diffuser. The CSL was easily spotted from the front due to the large round hole in it's bumper for it's secondary air intake. The boot lid had an integrated yet subtle spoiler rather than an add on lip.

The suede covered three spoke Motorsport steering wheel had but one button and it's purpose was to toggle the M-Track mode adjusting the throttle response and DSC. The normal stereo buttons (if the car had one) and cruise control were moved.

It was only available with the SMG II gearbox, which to my mind is a shame. The CSL was sold with 19" wheels shod in specially made Michelin Pilot Sport Cup semi-slick racing tyres tyres which only designed for use in the dry. Buyers had to sign a disclaimer saying they understood this shortcoming.

This wasn't and isn't a "super M3" for every day use. As for being lightweight 110kg is only about 7% so it's nice but not radical. The deletion of stereo, aircon and the dry weather tyres were a rather large hint by BMW that this wasn't a car to be driven to work every day. Rather it was for nice weekends and track days. In that regard a two seater version with a roll cage would have made more sense, that's what they've done in the 2016 M4 GTS and it really is a better plan despite the scary price premium.

M3 CS / ZCP

Called CS (not ClubSport) in the UK but ZCP in the US this M3 special edition was a fairly inexpensive upgrade over the normal car, a sort of track pack. The engine, drivetrain and other major components of the car are unchanged.

The options fitted included staggered 19" forged alloys in the same style as the CSL but not the same widths and heavier. These were standard on 2005 M3s.

Inside the car had the CSL steering wheel with a nice alcantara cover that was also used for the handbrake. This meant it gained the M button but lost the cruise and stereo buttons. The steering rack was the faster CSL version and the brakes were upgraded to CSL spec.

M3 GTR V8

The GTR V8 was a rare M3 first seen in early 2001. It had a four litre V8 that made almost 500bhp and had it's roots in the AC Schnitzer stable. Schnitzer raced competition versions in ALMS (American Le Mans Series) during 2001. Ten homologation cars were sold but to continue racing many more were needed and the factory decided to stop competing instead. This isn't surprising as the road cars cost around 150,000 GBP.

 

BMW E46 M3 SMG

SMG gear knob and speed selector.

SMG II Gearbox

Sequential Manual Gearbox II was optional on M3s and standard on the CSL. It was an evolution of the system first used on the E36 M3 and involves a normal gearbox with a single clutch operated by hydraulics under computer control. The system is operated by a +/- gearknob and/or paddle shifters. It is NOT an automatic transmission and cannot be driven as one. SMG-II weighs around 9kg more than a manual.

Unlike the first generation the speed of the shift is selectable in seven increments from quick to crazy by means of a control next to the gear lever. A harshness control would be a good way to describe it with the quickest settings being for track use only and having little mechanical sympathy.

As with all things a bit of maintenance goes a long way and every gearbox loves a fluid change but seldom sees one. The hydraulic pump can fail as can the electronics such as the charge relay. It's not a bad system but unless you really want it and can afford to fix the thing if it breaks a manual might suit you better. It actually CAN be fixed unlike the current versions which demand replacement of the entire gearbox! Progress.

This system was only fitted to the M3. Other E46s have a cheaper version which is unrelated.

 

BMW E46 M3

A severe case of rear subframe failure in an M3.

The Glass Jaw

The M3 is a strong, reliable car with an excellent body and mechanicals. The whole thing is a superb package and an excellent used buy. There's always a BUT. With the E36 M3 Evo it was the VANOS gear and with the E46 it's the rear subframe.

Z3 //Ms, E36 and normal E46s could all suffer from torn subframes around the four mounting points but it's wasn't that common. Even a 318 could see it so the idea that power alone was the cause seems unfounded. Yet the M3 sees it more than other models by some margin and here power and driving style must surely be factors.

The subframe's metal can be literally ripped apart around the mounting points. It starts with small cracks that may be hard to see as they can be hidden by dirt and obscured by the subframe itself. But they will most certainly grow in size once stared and can grow to over a foot long leading to complete and unfixable failure.

If caught in time the subframe can be lowered and strengthening plates welded in. BMW did this under warranty on cars up to ten years old so check the service history. But now there is no recourse and specialist such as Redish Motorsport charge around 1500 for the work. If you're buying an M3 or any E46 get it up on a ramp and check it. If you own one ask the MoT tester to pay special attention to the subframe every year and nip cracks in the bud if they occur.

Avoid the SMG box too. It's not fundamentally unreliable but if it does fail it's going to cost 1000's to fix.