Review: BMW E93 M3 Convertible (2008-13)

Review: BMW E93.I M3 Convertible (2008-10)

Overview

Released in Australia in December 2008, the BMW E93 M3 was a high-performance convertible with a retractable hard-top roof. Manufactured in Regensburg, Germany, the rear-wheel drive E93 M3 was powered by a 4.0-litre V8 petrol engine that was mated to either a six-speed manual or seven-speed double clutch transmission (DCT).

S65B40 engine

The 3999 cc S65B40 V8 petrol engine had a two-piece Alusil crankcase with reinforcing bedplate that was produced at BMW’s light-alloy foundry in Landshut, near Munich – this foundry was also used to produce Formula 1 engines for BMW Sauber. The S65B40 engine featured a forged crankshaft that ran on five bearings, fracture-split connecting rods, aluminium alloy cast pistons with an iron coating, an aluminium alloy cylinder head, eight individual throttle butterflies, hollow-cast double overhead camshafts, double VANOS variable intake and exhaust camshaft phasing, four valves per cylinder, a compression ratio of 12.0:1, two oil pumps and wet sump lubrication for oil supply up to 1.4 g. The S65B40 engine had an 8400 rpm rev limit.

Like the E60 M5 ‘s S85B50 V10 engine , the S65B40 engine’s MS S60 engine management system used ionic current technology to detect engine knock, misfiring and combustion misses. The ionic current satellite received signals from the five spark plugs of each cylinder bank. Depending on engine load, the satellite amplified these signals and transmitted them to the engine management system for analysis.

The E93 M3 could accelerate from rest to 100 km/h in 5.3 and 5.1 seconds with the manual and double clutch transmissions, respectively. The M3 Convertible’s top speed was electronically limited to 250 km/h.

As part of BMW’s EfficientDynamics program, the M3 was fitted with BMW’s ‘Brake Energy Regeneration’ which controlled alternator output to charge the battery when the vehicle was braking or coasting. Furthermore, an indicator would illuminate in the instrument panel to indicate the optimum gearshift point for fuel efficient driving.

Manual and M double clutch transmissions

The E92 M3 Coupe was initially offered with a six-speed ZF ‘Type G’ manual transmission which had the following gear ratios: 4.055 (1st), 2.369 (2nd), 1.582 (3rd), 1.192 (4th), 1.000 (5th) and 0.872 (6th); final drive ratio was 3.846.

The double clutch transmission (DCT) combined two gearbox components in a common housing and featured two oil-cooled wet clutches. One of the clutches operated the even gears (i.e. 2, 4 and 6), while the other clutch operated the uneven gears (i.e. 1, 3, 5, 7 and reverse). When driving, one of the clutches was always closed and the other open. When up- or down-shifting, the transmission control unit would pre-select the next gear and the clutches would be activated in an alternating process such that one clutch would open just as the other was closing.

The DCT had automated and manual gearshift modes, with eleven selectable shift settings: five shift programs for the automatic mode and six shift programs in the manual mode (including Launch Control). In manual mode, gear selection could be performed via the gear lever or steering wheel gearshift paddles. Gear ratios for the DCT were 4.780 (1st), 2.933 (2nd), 2.153 (3rd), 1.678 (4th), 1.390 (5th), 1.203 (6th) and 1.000 (7th); the final drive ratio of the DCT was 3.154.

Dimensions and body

Compared to the E46 M3 Convertible which preceded it, the E93 M3 Convertible was 123 mm longer (at 4615 mm), 24 mm wider (1804 mm), 22 mm taller (1392 mm) and had a 30 mm longer wheelbase (2761 mm). Significantly, the E93 M3 Convertible had an electro-hydraulic roof with fully automatic operation that could be lowered in 22 seconds.

The E93 M3 Convertible had a kerb weight of 1885 kg, or 1905 kg with the DCT. Compared to the E93 3-Series Convertible , mass reduction measures included:

• Lightweight long-fibre thermoplastic carriers beneath the front and rear bumpers (6 kg mass reduction);
• Long-fibre-reinforced plastic for the rear seat through-loading facility (7 kg mass reduction).

Suspension

The E93 M3 Convertible had a two-joint spring strut front axle and five-link independent rear suspension. The suspension also included BMW’s ‘Electronic Damper Control’ (EDC) which consisted of electronically-controlled dampers that continually adjusted according to road conditions. The driver could also select from ‘Comfort’, ‘Normal’ or ‘Sport’ drive modes. Compared to the standard E93 3-Series Convertible , changes for the E93 M3 included:

• A modified front subframe;
• A reinforced front spring strut;
• Forged alloy control arms, camber struts and wishbone;
• Wider track and revised suspension geometry (front and rear);
• Stiffer bushings (front and rear);
• Steel ball joints in place of some rear bushings;
• Unique shock absorber and damper rates; and,
• 28.0 mm diameter front and 23.6 mm rear anti-roll bars.

Steering

The E93 M3 had rack and pinion steering with a fixed ratio of 12.5:1 that was 22 per cent faster than the E93 3-Series. Furthermore, power assistance (BMW’s ‘Servotronic’) varied according to vehicle speed and whether Comfort or Sport drive modes were selected.

Safety equipment

Standard safety equipment for the E93 M3 Convertible included dual front airbags, front seat-mounted side airbags, ABS, electronic brake force distribution, brake assist, electronic stability control, traction control, front and rear seatbelt pretensioners and front seatbelt load limiters; the M3 Convertible also had a rollover sensor which, if triggered, would deploy rollover hoops to better protect the occupants. From September 2008, the M3 Convertible was fitted with active front seat head restraints.

The MK60ES electronic stability control system (BMW’s ‘Dynamic Stability Control’) was jointly developed by Teves and BMW. In addition to the conventional stability control operation of braking individual wheels to prevent wheelspin, the system included the following functions:

• Brake Standby: prepared for hard braking by pressuring the pad against the rotor when the driver abruptly reduced throttle input;
• Brake Drying: to keep the brake pads dry, the brake pad was pressed against the rotor when the rain sensor detected moisture; and,
• Start-Off Assistant: applied the brakes for one second after the driver’s foot was removed from the brake pedal for uphill acceleration from rest.

The DSC system could be completely switched off or, in M Dynamic Mode (MDM), provide higher wheel slip and yaw thresholds before intervening.

Brakes

The E93 M3 Convertible had 360 mm by 30 mm vented and cross-drilled front brake discs and 350 mm by 24 mm vented and cross-drilled rear discs. The two-piece discs consisted of an aluminium inner hat and a cast iron outer section that were connected by steel pins; single-piston calipers were fitted front and rear.

Features: M3 Convertible

Standard features for the M3 Convertible included 18-inch M light-alloy wheels (double-spoke style 260 M) with 18 x 8.5J 245/40 ZR18 front and 18 x 9.5J 265/40 ZR18 rear tyres, BMW’s ‘HiFi Professional Logic7’ sound system with thirteen speakers, a six-disc CD changer and auxiliary inputs (3.5 mm/USB), BMW’s ‘Professional Navigation’ system with an 8.8-inch colour monitor, TV tuner and voice recognition, Bluetooth mobile phone preparation, power adjustable and heated ‘M’ front seats, Novillo leather upholstery, climate control air conditioning, cruise control, adaptive bi-xenon headlights with washers, high-beam assist, automatic headlights, rain-sensing wipers, front and rear parking sensors (BMW’s ‘Park Distance Control’), a rear fog light, remote central locking with proximity key (BMW’s ‘Comfort access’), power windows, power adjustable and heated door mirrors with power folding function, automatic dipping of the passenger side mirror on reverse, a height and reach adjustable steering wheel, an electrochromatic rear view mirror, driver memory settings (seat and mirror position), push-button start, Anthracite headliner, front reading lights and illuminated vanity mirrors, a 12 volt power socket in the luggage compartment, tinted windows, tyre pressure monitoring, a trip computer, an alarm and immobiliser.

Inside, the M3 Convertible had ‘SunReflective’ leather upholstery that could remain up to 20 degrees Celsius cooler than conventional leather when exposed to the sun. Furthermore, the E93 M3 Convertible was fitted with conventional, non run-flat tyres (unlike the standard BMW E93 3-Series Convertible).

M Differential Lock

Fitted as standard, the M Differential Lock was a variable, rev-sensing differential on the rear axle that could provide a locking effect of up to 100 per cent to improve traction in adverse conditions. 

M Drive

First introduced in the BMW E60 M5 , the ‘MDrive’ system enabled the driver to customise their preferences with respect to the DCT transmission, throttle response (two modes), EDC damping, Servotronic steering assistance and DSC activation. These preferences could then be programmed (via iDrive) to activate to be engaged when the ‘M’ steering wheel button was pressed. 

September 2008 and 2009 updates

In September 2008, an upgraded iDrive system was introduced with favourite buttons. In September 2009, the climate control panel was revised and included buttons for the heated seats.

Review: BMW E93.II M3 Convertible (2010-13)

Overview

Production of the BMW E93.II (or E93 LCI) M3 Convertible commenced in March 2010. Visually, however, changes were limited to the introduction of full-LED tail-lights.

Features

Initially, standard features for the E92.II M3 Coupe were unchanged. In September 2010, however, upgraded Bluetooth functionality with audio streaming was introduced. 

EfficientDynamics: Start/Stop

From September 2010 production, the S65B40 engine had an Automatic Start/Stop function which enabled the engine to shut down when the vehicle was stationary in traffic to minmise fuel consumption.

Related links

• Specifications: BMW E93.II M3 Convertible (October 2011)
• M Registry: BMW E90, E92 and E93 M3
• Wikipedia.org: BMW E90 3-Series