The secret is out: supercar power is coming to the homegrown Commodore to create fastest Holden of all time.

Talk about going out with a bang!

Holden will build a Commodore with more power than a Lamborghini as a high octane farewell present before the Adelaide production line falls silent next year.

The fastest and most powerful Commodore ever made will also be the most expensive, expected to cost in excess of $165,000 -- almost twice the price of the dearest model on sale today.

It will be the last V8 sedan made locally, and the most powerful vehicle produced in more than 100 years of Australian car manufacturing.

Holden declined to comment on "future model plans", however News Corp Australia can exclusively reveal General Motors in Detroit has finally given the green light to build a Commodore powered by the supercharged "LS9" V8 from the Corvette ZR1.

The swansong supercar will eclipse the power of the current Commodore flagship -- the Holden Special Vehicles GTS -- with performance that will outpace the latest Porsches and Ferraris.

It will only be available with a manual gearbox because the engine has too much power for an automatic.

With in excess of 600 horsepower (or 475kW in modern terms) the limited edition will have more grunt than a V8 Supercar racing machine.

Fewer than 250 are expected to be built, as there are only a limited number of these particular supercharged V8 engines available out of the US.

Holden dealers have been inundated with enquiries following speculation on internet forums -- but the project is so secret they too are in the dark.

Fan gossip says the car will be called "GTS-R", a reference to a limited edition from 1996. But News Corp Australia understands the new super sedan will have a unique name to reflect its exclusivity.

The supercar will be made by Holden Special Vehicles, a separate Melbourne-based firm that has been building Holden's performance models for 29 years after the break-up with racing legend Peter Brock.

Part of the reason the Holden supercar is so expensive is because it will be built in a partially complete form on the Adelaide production line with the supercharged engine and gearbox from the HSV GTS -- which will then be replaced by the "LS9" V8 at HSV in Melbourne.

It is not the first time HSV has performed a heart transplant.

In 2008 the company replaced the "donor" Holden engine with a massive 7.0-litre V8 from a racing version of the Corvette; in the end 137 HSV W427 cars were built at a cost of $155,500 each. Production ended prematurely in 2009 as the Global Financial Crisis took hold.

With buyers holding out for the last locally made Commodores, Holden is confident the supercar will be an instant sellout -- especially as the imported Commodore due in 2018 will only have four-cylinder and V6 power.

Holden's hot rods

2008: HSV W427

Engine: 7.0-litre V8

Power: 375kW/640Nm

Price: $155,500

Why it is special: It is the biggest engine (in capacity) ever fitted to an Australian made car.

2013: HSV GTS

Engine: Supercharged "LSA" 6.2-litre V8

Power: 430kW/740Nm

Price: $96,990

Why it is special: It is the most powerful car ever made in Australia (to date), eclipsing the W427.

2017: HSV Final Edition

Engine: Supercharged "LS9" 6.2-litre V8

Power: 475kW/820Nm

Price: $165,000 (estimated)

Why it is special: It will go down in history as the most powerful Australian made car of all time.

How it will get built

Holden will build the new supercar in partially complete form as a HSV GTS on the production line in Elizabeth, near Adelaide.

The cars will then be transported to HSV at Clayton, near Melbourne, where the GTS supercharged V8 and transmission will be removed and the new "LS9" supercharged V8 and heavy duty transmission will be installed.

Other performance parts, such as bigger brakes, wheels, bodykit and exhaust will also be fitted at HSV in Clayton.

The as yet un-named supercar will then get transported to selected Holden dealers (65 of 220 across the network).

What will it be called?

Web forums speculate it will be called GTS-R, a reference to the special edition made in 1996 (of which just 85 were built). But News Corp understands HSV is planning on a unique name for its final homegrown hero car.

Why has it been so secret?

HSV had to meet strict global reliability standards set by General Motors in Detroit and it has taken until now to validate the engine transplant process and other engineering changes, including bringing the engine up to Euro V.

Are you signing yourself up to get on the list for fastest Holden ever? Let us know in the comments below.