Marilyn - Holden's Convertible Monaro

It's been hinted at for aeons, former Holden supremo Peter Hanenberger was believed to have owned one, and now Holden has finally come clean.

In one of the Australian automotive industry's longest-standing mysteries, Holden has let the cat out of the bag by confirming the existence of a V8-powered convertible Monaro coupe.

Sadly for those hoping to get their hands on the car, it is but a one-off vehicle, and will never reach production.

Codenamed 'Marilyn' - which pays hommage to the car's Aussie slang name 'Munro' - the drop top was built by the now defunct TWR Engineering in 2002 at a cost of $2 million.

After Holden design guru Mike Simcoe broached the subject of a drop top Monaro at the Geneva Motor Show back in 2001, the Holden Board of Directors requested an investigation into whether a convertible program was possible.

According to Holden, in-depth financial analysis confirmed that the costs associated with producing a current platform coupe convertible could not be justified. Not on the current platform anyway.

But when you look at other V8 convertibles that cost more than $200-grand, such as the BMW 645Ci, one wonders how much exactly Holden would have needed to charge customers to make a solid business case for the Monaro soft top. $92,000 perhaps?

Although the Monaro convertible will never see the inside of a Holden or HSV showroom, it's still a very pretty car, and when it's packing the General's standard issue weapon - the 5.7-litre, 16-valve V8 - it would have made for one of the faster drop tops on Australian roads.

And just imagine the sound from the stainless steel exhaust system with the top down, as the 351 cubic inch V8 small-block warbles and wob-wobs about its merry way.

Road Test editor Feann Torr test drove one of Holden's Monaros (which sells as a Pontiac GTO in the states) back in September 2003, and he had plenty of praise for the big V8.

"To be frank, I was expecting a low-tech, old world, dated and clunky bucket of bolts, but even with 20,000 kays on the clock, I found the 5.7-litre V8 to be a solid and - dare I say it? - very willing performer," Feann wrote.

Suffice it to say, everyone at Web Wombat Motoring was blown away by the new convertible images, and instantly crestfallen when they found out the vehicle would never be built. Damn shame that.

The conservatively-styled Monaro convertible gets a fully lined and insulated black canopy, which was designed as a six-bow system to retain the coupe's styling, and roof operation is fully automatic with a "competitive" cycle time according to Holden.

Amongst the changes needed to successfully complete the task were changes to A-pillar assemblies, rear quarter body panels, trunk lid outer and the doors were modified to take a frameless glass system.

There were reinforcements made on the underbody and mountings for a bolt-on cruciform structure to help optimise structural requirements.

The Marilyn concept was built by contractors TWR Engineering and Edscha in Europe two years ago, which Holden showed at a unique event in Melbourne [Australia] highlighting a dozen hallmark concept cars from Holden and its partners, dating back as far as the 1970 GTR-X.

The Monaro concept car was a surprise attendee at the event which brought together some of the defining vehicles of Australian motor shows.

These included the original Coupe (Monaro) concept that stole the 1998 Sydney International Motor Show; and two joint projects for Holden and Holden Special Vehicles – HRT427 from 2002 and the Coupe4 all-wheel-drive from the 2003 Sydney show. Click here for the low-down on all things Holden at the '03 Sydney Motor Show.

Other one-off vehicles included the GTR-X, one of Holden's first concept vehicles dating back to 1970, the reincarnation of the Sandman panel van from 2000, the SSX all-wheel-drive hatch from 2002 and UTEster utility from 2001, YGM1 sport utility, Cross 8 and recent 2004 Melbourne Motor Show standouts – SST, Elfin MS8 Clubman and MS8 Streamliner. Check out the Reports page for more info on these models.

The event, which was held at Flemington Racecourse, was the first time such an array of concept vehicles (conservatively valued at $25 million) had been shown by any Australian carmaker.

Holden's Executive Director [GM] of Asia Pacific Design, Michael Simcoe, stated that Holden's concept vehicles had played an integral role in showcasing the Australian marque's design prowess on the world stage.

"Concept cars characterise everything that is exciting about the creative process in automotive design. They can transform people's perceptions of what is possible in terms of design and engineering," said Simcoe.

"There is no doubt that the Coupe Concept provided the catalyst for all that came after, because it allowed us to believe in ourselves. It gave us permission to push forward and continue to create, through these vehicles and those to come, a clear and strong vision of what Holden is and where it intends to go.

"The TWR Engineering brief for Marilyn was to produce a convertible design based on minimum changes to the coupe," concluded Simcoe.

While the Marilyn concept based on the VT-VZ Commodore's underpinnings has now been scuppered, the VE Commodore could still bring a few pleasant surprises.

GM's global 'Zeta' platform, which will underpin the new VE Commodore and Monaro due in 2006, could spawn a convertible Monaro-themed vehicle, and the word on the street says you can get one in 2007. Stay tuned to the News section for more developments.