New 602kW Lamborghini Sian Roadster debuts

Lamborghini has launched a new ultra-exclusive Sian Roadster hypercar overnight that features an even more powerful hybrid version of its naturally-aspirated V12.

Limited to just 19 vehicles, the famous Italian manufacturer says the latest roofless version of the Sian coupe it revealed last year is the most powerful Lamborghini road car ever.

Powered by a development of the same supercapacitor-assisted, 48-volt 6.5-litre V12 engine, the new Sian Roadster produces an incredible 602kW. For reference, that's more than 800hp in the old money.

Like the hard-top version, all that power equates to a 0-100km/h sprint of less than 2.9 seconds (0.1sec slower than the coupe) and a top speed of about 350km/h.

Converting the sharp-edged coupe to convertible has been no mean feat, although engineers made their task slightly easierby deleting the roof completely – without any replacement.

That means there's no retractable roof, or even a fabric tonneau offered in the event of an emergency downpour.

Most of the work has involved adding the rollover hoops and ensuring the revised aerodynamics provide a mixture of keeping the roofless Sian stable at extremely high speed while feeding enough air to keep the naturally-aspirated V12 cool while spinning up to 8500rpm.

Rumoured to preview design elements that will be included on the next-gen Aventador due in 2024, the hybrid roadster retains the coupe's Y-shaped LED headlamps, gaping-wide side intakes and periscope vents that sit on the rear wheel arches.

At the rear, the same hexagonal LED tail lamps and pop-up rear wing feature above a diffuser that looks lifted from a Le Mans racer.

Inside, the lightweight roadster keeps much of the coupe's cabin, with the open-air Lambo getting white and grey seats that are matched with blue detailing. For production, customers will be offered 3D printed air vents that can be personalised with their initials.

Under the rear boot lid is, no doubt, the star if the show. The reason supercapacitors were chosen is because of their ability to charge and deploy quicker than batteries and their significant weight advantage.

Providing enough power for an extra 25kW boost, the system adds only 34kg of mass and allows the Sian to travel up to 130km/h for 10km on pure-electric power alone.

The same electric motor also overcomes the drawbacks of the single-clutch automated manual transmission, torque-filling for smooth upshifts and downshifts.

It's also used for reversing the Sian and low-speed manoeuvres – another place where the Aventador's transmission struggles.

Back in 2019, Lamborghini said it would make just 63 examples of the Sian FKP 37, each priced at $3.6 million ($A5.2m). It’s thought the even more limited roadster will sell for a price tag that far exceeds the coupe.

Sadly, if you fancy the advanced electrified droptop Lambo to add to your car collection, you're too late. All 19 cars are already spoken for.