Lamborghini Sian Roadster revealed with supercapacitor-powered hybrid V12, limited to 19 units

Tuhin Guha Updated: July 08, 2020, 11:06 PM IST

After the debut of the hard-top version last year, Lamborghini has now taken the wraps off the Lamborghini Sian Roadster. This open-top version is even rarer than the earlier car, limited to only 19 units. Like with the roadster, all 19 have been spoken for.

The loss of the roof has had little effect on the Sian's numbers. Only the 0 to 100 kmph time has dropped by 0.1s to 2.9s while top-speed remains unchanged at 350 kmph. The Roadster uses the same hybrid powertrain, the most powerful ever fitted to a Lamborghini, as the coupe. This uses the 6.5-litre V12 from the Aventador SVJ but with titanium intake valves. The combined power output is 819PS with 785 coming from the V12. A 48V electric motor has been incorporated into the gearbox which allows for it to be directly connected to the wheels for the first time. Just this 34PS motor can be used during low-speed manoeuvres like parking and reversing.

This e-motor, unlike other such units which use a lithium-ion battery, is powered by a supercapacitor. This allows for it to be three times more powerful than a battery of the same weight. The Sian's unit is placed between the cockpit and the engine and weighs only 34 kgs, allowing for a quite remarkable 1PS/kg weight to power ratio. Another useful trait of this system is that it allows for the battery to be charged and discharged with the same efficiency and power. This allows for the Sian to have a unique regenerative braking system which lets it's energy storage system be fully charged every time the vehicle brakes. This boost is available up to 130 kmph when the e-motor disconnects.

The Sian's regenerative braking system allows for an instant power boost, akin to a fully electric car and making the Sian 10 per cent faster than a car without this system. This also adds more traction, with a 10 per cent increase available up to third gear. Another benefit is its torque-fill functionality, that smoothes out power delivery during gear shifts.

Expectedly, the styling is more-or-less identical to the FKP 37. Like that car, there are quite a few similarities to the Terzo Millenio concept from 2017. This is evident in the extremely angular elements all throughout the car. There are the Y-elements in the front headlamps and more aero bits which highlight the Sian's unique look. But the overall shape takes quite some inspiration from the Countach, which even carries over when viewed with the roof off. This is evident in the cuts on the bonnet, the window line and in the glass-area itself.

Further back, the NACA air ducts, the hexagonal elements in the rear, including the taillamps and the spoiler all take inspiration from Gandini's original. All these bits aid aero and cooling functionality. In the roadster, the airstreams behind the seats are a distinct styling element and further relate to the angular Lamborghini look. Another notable touch that highlights the Sian's look are the Countach-inspired hexagonal taillamps.

Unsurprisingly, the entire design hides a high degree of functionality. The airflow is directed from the front splitters through the front bonnet, passes through the side air intakes, then the outlets and over the rear spoiler. The loss of the roof has not affected aerodynamic efficiency when compared to the roadster. A unique bit of tech are the cooling vanes at the rear. These work to cool the exhaust system when triggered by smart materials in the exhaust outlet.

The interiors are more sedate, keeping in line with other Lamborghinis so you have the new touchscreen infotainment unit that debuted in the Huracan Evo, the toggle switches and Lamborghini's version of the virtual cockpit, among other things.

Each Sian Roadster can be individually configured via Lamborgini's Ad Personum service. For example, this car's white with Blu Glauco detailing and aluminium elements in Oro Electrum. With the Aventador bowing out imminently, the Sian with its hybrid powerplant is a very strong indicator of where Lamborgini's storied line of V12 mid-engined supercars are headed.