Like the striking Sian hard-top revealed at the Frankfurt Motor Show last year, the Roadster draws most of its power – some 774 hp – from an upgraded version of the naturally aspirated 6.5-liter V12 from the Aventador and has a 48 V 34 hp electric motor built into the gearbox for low emission zero emission maneuvers.
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The electric motor is also used to flatten the acceleration curve of the Sián, going into action to provide torque filling that mitigates the effects of deceleration when changing gears. An added benefit of this, says Lamborghini, is that “the driver will only feel the drop in acceleration, eliminating the uncomfortable jerky movements.”
As a result, the Sián Roadster is expected to send the sprint from 0 to 62 mph faster than the 2.9sec of the conventionally powered Aventador SVJ Roadster and its top speed is set at over 217 mph. A weight less than 1650 kg is claimed, although we do not yet have an indication of the weight of the hard-top for comparison.
When the hardtop was revealed, Lamborghini claimed that adding an electrical element to the V12 engine did not affect the branded sound of the powertrain.
Both versions of the Sián can use a supercapacitor energy storage unit – supposed to store 10 times more energy than a conventional lithium-ion battery – to provide instant torque increases at will while traveling to speeds of up to 81 mph.
The device, which comes from the one used to power the Aventador starter, weighs only 34 kg, offering a power / weight ratio of 1 ch for 1 kg and guaranteeing a minimal impact on performance. Symmetrical power flow means that it charges using the energy recovered from braking at the same rate as discharge, providing maximum efficiency.