Item: 2014 BMW F83 M4 Convertible
Rating: 3.5

Responsive and flexible 3.0-litre twin-turbo engine
Excellent dynamics
Adaptive suspension provides range of settings
Open-top appeal

Convertible body lacks rigidity of coupe, shakes over bumps
Dynamics fall short of F82 M4 Coupe
Artifical steering feel
Small boot

Review: BMW F83 M4 Convertible (2014-17)

Overview

Released in Australia in October 2014, the BMW F83 M4 was a high-performance convertible with a power-operated metal roof; the related F82 M4 Coupe has been reviewed separately. Manufactured in Regensburg, Germany, the F83 M4 Convertible was powered by BMW’s turbocharged 3.0-litre S55B30 six cylinder engine which was mated to either a six-speed manual transmission (with throttle blipping) or a seven-speed double clutch transmission (DCT).

S55B30 Engine

The S55B30 engine had a die-cast aluminium alloy block, a closed-deck crankcase, an aluminium cylinder head, a forged steel alloy crankshaft, double overhead camshafts, four valves per cylinder, two parallel Mitsubishi TF035 turbochargers which provided maximum boost pressure of 1.3 bar (18.85 psi), variable intake and exhaust camshaft timing (BMW’s ‘dual VANOS’), variable intake valve timing (‘Valvetronic III’) and a compression ratio of 10.2:1. Maximum engine speed for the S55B30 engine was 7600 rpm.

To minimise fuel consumption, the S55B30 engine had a ‘Start Stop’ function which enabled it to shut down when the vehicle was stationary and BMW’s ‘Brake Energy Regeneration’ which varied alternator output when the vehicle was coasting or braking to recharge the battery. With the DCT, fuel consumption for the M4 Convertible was 8.7 litres per 100 km over the combined ECE 93/116/EU driving cycle.

The M4 Convertible could accelerate from rest to 100 km/h in 4.6 seconds with the manual transmission and 4.4 seconds with the DCT.

Manual and M double clutch transmissions

The six-speed manual transmission had a double-plate clutch and carbon friction linings in its synchronizer rings. Previously reserved for BMW’s double clutch transmission, the manual transmission would blip the throttle on downshifts for smoother shifts and greater stability. Furthermore, the manual transmission was 12 kg lighter than its predecessor in the E93 M3 . Gear ratios for the manual transmission were 4.110 (1st), 2.315 (2nd), 1.542 (3rd), 1.179 (4th), 1.000 (5th) and 0.846; the final drive ratio for the manual transmission was 3.462.

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 selectable shift settings; in manual mode, gear selection could be performed via the gear lever or steering wheel gearshift paddles. Gear ratios for the DCT were 4.806 (1st), 2.583 (2nd), 1.701 (3rd), 1.277 (4th), 1.000 (5th), 0.844 (6th) and 0.671 (7th); the final drive ratio for the DCT was 3.462. The DCT also featured:

A ‘Smokey Burnout’ function permitted a degree of rear wheel spin while the car was moving at low speeds; and,
A Stability Clutch Control function that would ‘open the clutch when the car was understeering to bring it back into line’.

Dimensions

Compared to its E93 M3 Convertible predecessor, the F83 M4 was 56 mm longer (at 4671 mm), 66 mm wider (1870 mm), 6 mm lower (1386 mm) and had a 51 mm longer wheelbase (2812 mm). With its roof in position, the F83 M4 had a drag coefficient of 0.34 Cd.

The F83 M4 Convertible had an unladen weight (EU) of 1790 kg for models with the manual transmission and 1865 kg with the DCT; Mass reduction measures included:

Aluminium suspension components (see ‘Suspension’, below);
An aluminium bonnet;
A CFRP driveshaft that was constructed as a single piece – without a centre bearing – and was 40 per cent lighter than its predecessor.

Cargo capacity was 370 litres with the roof up and 270 litres when it was lowered

Suspension

The F83 M4 had double-joint spring strut front suspension and five-link rear suspension. The suspension also included electronically-controlled dampers (BMW’s ‘Adaptive M suspension’) continually adjusted to driving conditions and behavior, and enabled the driver to select from ‘Comfort’, ‘Sport’ and ‘Sport+’ settings via BMW’s ‘Driver Experience Control’.

For the front axle, aluminium was used for the control arms, wheel carriers and axle subframes for a 5 kg mass reduction relative to a conventional steel design. The suspension also included play-free ball joints and elastomer bearings (developed specifically for the F80 M3 Sedan , F82 M4 Coupe and F83 M4 Convertible), an aluminium stiffening plate, CFRP precision strut and additional bolted joints between the axle subframe and the body structure for greater front end rigidity.

For the rear axle, the control arms and wheel carriers were manufactured using forged aluminium, while there was a rigid connection (i.e. without elastic rubber elements) between the rear axle subframe and the body to improve wheel location and directional stability.

Steering

The F83 M4 Convertible had electric, power-assisted rack and pinion steering in which the degree of assistance varied according to vehicle speed. The driver could also select from ‘Comfort’, ‘Sport’ and ‘Sport+’ modes.

BMW F83 M4 Convertible specifications
	Engine	Trans.	Peak power	Peak torque
M4 Convertible	3.0-litre twin-turbo petrol I6 (S55B30)	6sp man., 7sp DCT	317 kW at 5500-7300 rpm	550 Nm at 1850-5500 rpm
M4 Convertible Competition Package	3.0-litre twin-turbo petrol I6 (S55B30)	6sp man., 7sp DCT	331 kW at 7000 rpm	550 Nm at 1850-5500 rpm

Safety equipment

Standard safety equipment for the BMW M4 Convertible included dual front airbags, front seat-mounted side airbags, ABS, brake assist, electronic brake force distribution, electronic stability control (BMW’s ‘Dynamic Stability Control’ or DSC), traction control, corner brake control, front and rear seatbelt pretensioners, front seat load limiters and automatically deploying roll bars. The Dynamic Stability Control system had an ‘M Dynamic Mode’ which permitted a higher degree of yaw and wheelspin before intervening.

The M4 Convertible was fitted with BMW’s ‘Active Protection’ system which operated automatically at speeds above 18 km/h. If the front-mounted camera or radar detected an emergency braking manoeuvre or the onset of heavy understeer or oversteer, Active Protection prepared for a collision by retracting the front seatbelts and closing the side windows and sunroof. Following the initial impact, the system would apply the brakes for a further 1.5 seconds to reduce the likelihood of a second collision.

The M4 Convertible also had a permanent SIM card which provided BMW Teleservices and ‘Intelligent’ emergency call functions.

Brakes

The M4 had 380 mm front brake discs with four-piston calipers and 370 mm rear brake discs with two-piston calipers; both front and rear discs were inner-vented and perforated.

Features: M4 Convertible

Standard features for the M4 Convertible included 19-inch forged alloy rims (9.0J front and 10.0J rear) with 255/35 ZR19 92Y front and 275/35 ZR19 100Y rear tyres, a 500 watt harman/kardon surround sound system with twelve speakers, auxiliary inputs (3.5 mm/USB) and Bluetooth connectivity, BMW’s ‘Professional’ navigation system with an 8.8-inch colour screen, 20Gb hard-drive and iDrive touch controller, extended ‘Merino’ leather upholstery, dual-zone climate control air conditioning, BMW’s ‘Air Collar’ (neck heating), power adjustable and heated front ‘M’ sports seats (with driver’s seat memory settings), bi-xenon headlights, automatic headlights, rain-sensing wipers, front and rear parking sensors, a rear view camera, bird’s eye surround view function, through-loading rear seats, ‘M’ leather steering wheel with gearshift paddles, remote central locking, proximity key for keyless entry (BMW’s ‘Comfort Access’), power windows and mirrors, a height and reach adjustable steering wheel, electrochromatic rear-view and door mirrors, carbon fibre interior trim, illuminated vanity mirrors, ambient lighting, ‘M’ door sills, a trip computer and an immobiliser.

July 2015 update

In July 2015, standard safety equipment for the F83 M4 Convertible was extended to include:

BMW’s ‘Driving Assistant’:
- Approach Control Warning: if the driver was rapidly approaching an obstacle ahead, the driver would receive a visual warning in the instrument cluster, followed by a warning tone. If the driver failed to respond, the brakes would be applied automatically with deceleration of up to 3 m/s²;
- Lane Departure Warning (LDW): operating at speeds above 70 km/h, a camera could scan the road up to 50 metres ahead and detect lane markings. If the driver unintentionally deviated from their lane, the driver would be alerted via steering wheel vibrations and a visual warning in the instrument cluster;
- Pedestrian Warning with Light Braking Function: used a camera to scan the road ahead when the vehicle was travelling at speeds between 10 km/h and 60 km/h. if a potential collision with a pedestrian was identified, the driver would receive a visual warning in the instrument cluster and an alert tone; simultaneously, the braking system would be primed for maximum response. If the driver failed to respond, medium-force braking would be automatically initiated – this would reduce the risk of collision and prompt the driver to react. Once the driver applied the brake pedal, maximum braking force would be applied; and,
Lane Change Warning: used two radar sensors in the rear of the vehicle to monitor traffic in adjacent lanes with a range of up to 60 metres behind the vehicle. The Lane Change Warning would warn the driver of potentially dangerous situations by conveying warnings through the instrument panel, an LED icon on the door mirror and steering wheel vibrations.

As part of the July 2015 update, BMW’s ConnectedDrive Services and Apps were also introduced – this included BMW TeleServices which enabled service-related vehicle data to be automatically transmitted to the driver’s preferred service dealer and for vehicle diagnostics to be transmitted to the Roadside Assistance Centre for immediate assessment over the phone.

Furthermore, standard features for the F83 M4 Convertible were extended to include full Merino leather upholstery (including the instrument panel and glove compartment), adaptive LED headlights, Internet connectivity, BMW’s ConnectedDrive Freedom (which included internet-based services, remote services, real-time traffic information and concierge services), Internet connectivity, head-up display and tyre pressure monitoring.

Active M Differential

The F83 M4 Convertible was fitted with an electronically controlled, multi-plate limited-slip differential (BMW’s ‘Active M Differential’) that operated in conjunction with the electronic stability control system. As such, the degree of differential locking could range from 0 to 100 per cent to prevent wheelspin and improve traction. By way of example,

When lifting off the throttle, the differential would open such that the lock-up effect was zero for precise turn-in; and,
When accelerating out of a corner, lock-up would occur progressively – up to 100 per cent – for maximum traction.

BMW M4 Convertible Competition Package

The BMW F83 M4 Convertible with Competition Package was released in Australia in July 2016. Changes for the BMW M4 Convertible Competition included:

A more powerful S55B30 engine which produced peak power of 331 kW;
Forged, machine-polished 20-inch M alloy wheels with 666 M styling and mixed tyres (265/30 R20 front and 285/30 R20 rear);
For the ‘Adaptive M’ suspension, new springs (15 per cent stiffer), dampers, anti-roll bars and bushings, and reconfigured driving modes (Comfort, Sport and Sport+);
A revised ‘Active M’ differential; and,
Revised electronic stability control settings.

The BMW M4 Convertible Competition Package could be identified by its ‘BMW Individual’ high-gloss Shadow Line exterior trim for the side window trim, window recess finishers, door mirror frames, kidney grille, side gills and model badge. Inside, the M4 Convertible Competition Package had M leather seats with cut-out elements to reduce mass, while the seatbelts featured woven BMW M stripes.