Limited to just three discerning owners, the Spider is available for order from RM1,218,000 (before duties and options) and comes in three packages of Standard, Luxury or Performance.
Colour choices are plentiful with 23 colours in the palette which includes the newly added Belize Blue and Aztec Gold as well as Supernova Silver - a heritage colour first seen on the MP4-12C.
The Spider maintains its looks versus the Coupe variant with its top up as well as its wheelbase at 2,670mm at dimensions at 4,543mm-long, 2,161mm-wide (2,809mm with doors up) and 1,194mm-tall (1,953mm with doors up).
Power also comes from the same 4.0-litre (3,994cc) M840T twin-turbo V8 that's been mid-mounted between the cockpit and rear wheels - producing 720PS at 7,500rpm and 770Nm of torque at 5,500rpm and managed by a seven-speed Seamless Shift Gearbox for the rear wheels.
The Spider gets from 0 to 100kph in 2.9 seconds while the 200kph mark is reached five seconds later at 7.9 seconds - just 0.1 seconds off the Coupe's pace, before reaching a top speed of 341kph (325kph with the roof down).
With a power-assisted electro-hydraulic type steering system taking care of directional changes, outright mechanical grip comes from its 245/35 (front 19-inch) front and 305/30 (rear 20-inch) Pirelli P Zero tyres. Track-goers may want to opt for the P Zero Corsa or Trofeo R tyres from Pirelli as an optional extra.
Ride and handling are managed by the independent adaptive dampers with dual aluminium wishbones that work in unison with the Proactive Chassis Control II hydraulic suspension system.
The system provides three driving modes of Comfort, Sport and Track to help manage the 1,468kg (kerb) supercar's 42% (front) and 58% (rear) weight distribution.
For stopping power, the Spider has been fitted with six-piston (front) and four-piston (rear) callipers that clamp down on the 390mm (front) and 380mm (rear) cross-drilled carbon-ceramic discs.
While travelling at a stealthy altitude of 107mm, ramps can be attacked at a maximum of 8.3-degrees, but getting the optional lift system allows for a slightly more obtuse 10.4-degrees.
Like all McLaren cars, the new 720S uses a carbon fibre structure at its core, in this case, designated Monocage II-S where it is a development of the coupe variant - only without a 'spine' running down the rear above the cabin.
The rear section of the upper structure is where the Spider accommodates its retractable hardtop as has the header rail found across the top of the windscreen to integrate the central latching mechanism.
Even without the roof, the 1,468kg (kerb weight) supercar from the UK did not require reinforcements for the chassis.
Instead, the Spider received a beefed-up rollover protection system with the use of fixed carbon fibre structural supports integrated into the rear of the Monocage II-S that acts as the main anchor points for the roof system and seatbelts.
Overall, this has made the Spider 49kg (or just 4%) heavier than the 720S Coupe, but this is primarily associated with the addition of the retractable hard-top and tonneau system.
This hides a 58-litre storage space beneath it and takes all but 11 seconds to fully open or close while travelling at a maximum speed of 50kph -for more luggage room the front end has a more accommodating 150-litre storage compartment.
Further back, other than the slight protrusions of the dual tailpipes, a full-width active rear spoiler resides at the top and can automatically deploy to help increase downforce when needed as well as act as an airbrake under heavy braking.
Although the wing is identical to the Coupe's, its deployment mapping is bespoke to each body style in that the system can detect if the Spider's roof is up or down and will react accordingly.
The roof is a completely new design with a single carbon fibre roof panel as standard and uses electric motors to run virtually silent and can operate up to a maximum speed of 50kph - a carbon fibre-framed electrochromic glass roof that can switch between clear and tinted states at the touch of a button is available as an optional extra.
The canopy-like design of the cockpit is touted to provide an exceptional 360-degree vision and allows light to flood in - thanks to the low-profile glazed flying buttresses that help to guide airflow with its leading edges.
Lifting the dobule-skinned doors with soft-seal system presents the cabin that's been upholstered in the customer's choice of a two-tone colour combination with materials that include Alcantara or Nappa leather matched with machined anodised aluminium switches.
The high-resolution centrally-mounted 8.0-inch Central Infotainment Screen interface displays audio, media, navigation and climate controls among others, with all key applications shown on a vertical carousel as well as available via a quick-access 'hard' keys below the screen.
"As the most accomplished convertible supercar ever, the new Spider delivers across a remarkable spectrum of abilities to outstandingly high-levels, and as lightest in class with an increase of just 49kg over the 720S Coupe, moves us further ahead of our competition in the weight race," said McLaren Kuala Lumpur CEO Roland Chan.
With the arrival of the 720S Spider, it no joins its McLaren stablemates that include the 720S Coupe, 600 LT, 600LT Spider, 570S Coupe and 570S Spider.