Review: BMW G29 Z4 Roadster (2019-on)

Overview

Released in Australia in April 2019, the BMW G29 Z4 Roadster was a two-seat convertible with a power-operated soft-top roof. Manufactured by Magna Steyr in Graz, Austria, the rear-wheel drive BMW G29 Z4 Roadster range initially consisted of sDrive20i, sDrive30i and M40i variants, all of which had eight-speed automatic transmissions (see table below).

Body and dimensions

The BMW G29 Z4 Roadster was underpinned by BMW’s CLAR platform which was shared with the Toyota Supra. Compared to the BMW E89 Z4 Roadster , the G29 Z4 Roadster was 85 mm longer (at 4325 mm), 74 mm wider (1864 mm), 13 mm taller (1304 mm) and had a 26 mm shorter wheelbase (2470 mm); its drag co-efficient was 0.29 Cd. Relative to the E89 Z4 Roadster, the G29 Z4 Roadster also achieved:

• A 30 per cent increase in rigidity; and,
• A 60 kg mass reduction, in part due to the use of aluminium for the bonnet and doors, and plastic for the tailgate.

According to BMW, the G29 Z4 Roadster had a 50:50 front:rear weight distribution.

The G29 Z4 Roadster’s soft-top roof could be opened or closed in ten seconds, and while the Z4 Roadster was travelling at speeds up to 50 km/h. Whether the soft-top roof was open or closed, the G29 Z4 Roadster had a boot capacity of 281 litres.

Suspension and steering

The BMW G29 Z4 Roadster had a double-joint spring strut front axle with aluminium controls arms and swivel bearings to reduce unsprung mass. Beyond this, the five-link rear axle had aluminium and steel components.

Australian-delivered BMW Z4 sDrive20i vehicles were fitted with BMW’s ‘M Sport’ suspension which reduced ride height by 10 mm. Furthermore, the Z4 sDrive30i and Z4 M40i were fitted with ‘Adaptive M Sport’ suspension which lowered the ride height by 10 mm and included electronically-controlled dampers that reacted to driving conditions; the driver could also select from Comfort, Sport and Sport+ drive modes.

The BMW G29 Z4 Roadster had rack-and-pinion steering with adjustable power assistance (electric) and steering angle (BMW’s ‘variable sport steering’).

Safety equipment

Standard safety equipment for the BMW G29 Z4 Roadster included dual front airbags, front seat-mounted airbags with side and head protection, ABS, electronic brake force distribution, brake assist, electronic stability control, traction control, active front seat head restraints and front seatbelts with pre-tensioners and load limiters.

For Australian deliveries, AustralianCar.Reviews understands that the BMW G29 Z4 Roadster was fitted with the following safety technologies as standard –

• Collision Warning and Pedestrian Warning with City Braking: operating at speeds from 10 km/h to 60 km/h for pedestrian detection and up to 80 km/h for vehicle detection, the approach control warning system would initially warn the driver if there was a risk of a frontal collision. In its second stage, the braking system would be prepared for faster response and, if the driver failed to react, autonomous emergency braking (AEB) would be initiated to reduce vehicle speed;
• Lane Change Warning: active at speeds above 10 km/h, Lane Change Warning monitored the zones to each side of the vehicle. If the driver activated the indicators to change lanes, the system would checks these zones and – if occupied – warn the driver via steering wheel vibrations and flashing a symbol in the respective door mirror;
• Lane Departure Warning: active at speeds above 72 km/h, the driver would be alerted by steering wheel vibrations if the vehicle deviated from its lane without prior activation of the indicators;
• Rear collision prevention: if a rear-end collision was anticipated, following traffic would be warned by double frequency flashing of the hazard lights;
• Crossing traffic warning front: used radar sensors to check for approaching traffic at junctions with poor or impeded visibility;
• Crossing-traffic warning rear: when reversing out of a parking space, ‘Crossing-traffic warning rear’ would warn the driver of approaching traffic that may cross the driver’s projected path; and,
• Speed Limit Info: incorporated speed restrictions into the driver-selectable Speed Limiter function or Active Cruise Control (where fitted).

The BMW Z4 sDrive30i and M40i were further equipped with Active Cruise Control with Stop&Go function. At speeds from 30 km/h to 210 km/h, Active Cruise Control could maintain a speed-dependent distance from the vehicle ahead. With the Stop&Go function, the vehicle could apply the brakes to bring itself to rest and, once the traffic ahead began to accelerate, automatically accelerate if the vehicle had been stationary for a period of less than 30 seconds.

Wheels, tyres and brakes

Wheel, tyre and braking packages for the BMW G29 Z4 were as follows –

• Z4 sDrive20i: 8.0J x 18-inch front alloy wheels with 225/45 ZR18 tyres and 9.0J x 18-inch rear alloy wheels with 255/40 ZR18 tyres. Furthermore, the BMW Z4 sDrive20i had 330 mm by 24 mm ventilated front brake discs and 330 mm by 20 mm solid rear discs;
• Z4 sDrive30i: 9.0J x 19-inch front alloy wheels with 255/35 ZR19 tyres and 10.0J x 19-inch rear alloy wheels with 275/35 ZR19 tyres. The braking package for the Z4 sDrive30i and M40i consisted of 348 mm by 36 mm ventilated front brake discs and 345 mm by 24 mm solid rear discs; and,
• Z4 M40i: same wheels as the Z4 sDrive30i, but finished in ‘Cerium Grey’.

All BMW G29 Z4 Roadsters had a tyre repair kit as standard.

Features: BMW G29 Z4 sDrive20i

For Australian deliveries, the BMW Z4 Roadster was equipped with BMW’s ‘Live Cockpit Professional’ which consisted of a 10.25 inch ‘Control Display’ touchscreen in the centre console and a 12.3-inch digital instrument cluster. Powered by BMW Operating System 7.0, BMW’s ‘Live Cockpit Professional’ also featured an adaptive navigation system, a hard-drive-based multimedia system, two USB ports, Bluetooth and WiFi interfaces, and Apple CarPlay.

Beyond this, standard features for the BMW G29 Z4 sDrive20i included a HiFi sound system with ten speakers and a digital radio tuner (DAB), Vernasca leather upholstery, power adjustable and heated ‘M Sport’ front seats with memory settings, dual-zone climate control air conditioning, cruise control with braking, LED headlights, rain-sensing wipers, through-loading rear seats, an ‘M’ leather steering wheel, remote central locking, power adjustable mirrors with anti-dazzle function, power windows, a height and reach adjustable steering column, ‘Sensatec’ dashboard trim, wind deflector, ‘Aluminium Tetragon’ interior trim, a trip computer, an alarm and immobiliser.

As standard, the BMW G29 Z4 Roadster sDrive20i was also fitted with –

• BMW Head-Up Display: projected driving-related information onto the windscreen and into the driver’s field of view;
• BMW’s ‘Parking Assistant’: used ultrasonic sensors to detect parking spaces and controls acceleration, braking, steering and gear changes to manoeuvre the vehicle into the space; and,
• BMW’s ‘Reversing Assistant’: when exiting a parking space or manoeuvring in a confined area, the Reversing Assistant could control steering to reverse the vehicle along a path that it had recently travelled forwards, up to a distance of 50 metres. The Reversing Assistant was activated by pressing a button when the vehicle is stationary and the gear selector is in the ‘P’ position.

Features: BMW G29 Z4 sDrive30i

Compared to the BMW Z4 sDrive20i, the Z4 sDrive30i was further equipped with –

• BMW’s ‘Comfort Access’ (i.e. proximity key);
• Adaptive LED headlights: the high beam light was divided into four LED segments which – at speeds above 70 km/h – could be activated and deactivated independently when the front-mounted camera detected an oncoming vehicle; and,
• BMW Digital Key: used Near Field Communication (NFC) so that the G29 Z4 Roadster could be locked and unlocked from a smartphone. To unlock, the smartphone needed to be held up to the door handle. Once inside, the engine could be started as soon as the phone had been placed in the Wireless Charging or smartphone tray.

Features: BMW G29 Z4 M40i

The BMW Z4 M40i was distinguished by its harman kardon surround sound system which had 12 speakers, a digital amplifier and a total output of 464 watts, adjustable front seat lumbar support, ambient lighting and electronically-controlled limited-slip ‘M Sport’ rear differential. Available as an extra-cost option for the Z4 sDrive30i, the ‘M Sport’ differential had an electric motor which could generate a locking effect to limits speed equalisation between the inside and outside rear wheel when cornering – this enabled the outside wheel to rotate faster, thereby improving traction and reducing understeer.

Visually, the BMW Z4 M40i could be identified by its ‘Cerium Grey’ finishes for the front face and surrounds of the mesh-design grille, and trapezoidal exhaust tailpipes.

Specifications

• Specification Guide: BMW G29 Z4 Roadster (March 2019)

Related links

• BMW PressClub: The new BMW Z4 (September 2018)