CONJURING A WINDSCREEN OUT OF THIN AIR
It might not have a windscreen but the only thing eye-watering about McLaren’s ultra-exclusive Elva roadster is its $2.3m price tag, thanks to a brilliant aerodynamic trick.
Like many mid-engined cars, cooling air enters through the McLaren’s nose, flows over the heat exchangers housed within and exits via a large vent in the bonnet. However, the warmed air has a dual purpose. When the Active Air Management System (AAMS) is activated, a carbonfibre deflector rises 150mm out of the bonnet ahead of the vent, creating lower pressure at its leading edge. This aerodynamic depression causes the air exiting the top of the bonnet to accelerate vertically, creating what McLaren describes as a ‘bubble of calm’. The column of air creates an invisible wall where a windscreen would normally be located, minimising cabin turbulence.
Binning a windscreen at the design stage along with a roof and the pillars to support it saved significant kilos from the car’s final kerb weight. In fact, thanks also to cutting-edge carbonfibre construction techniques, the Elva is McLaren’s lightest production road car to date. An official kerb weight has not been announced, but McLaren’s claim means this topchopped bantamweight tips the scales at less than 1140kg.
McLaren says the AAMS deflector is ‘discreet’, but owners who would prefer to endure a little cabin turbulence rather than spoil the exterior lines at speed can manually override the system with the push of a button.
The AAMS improves the effectiveness of the air-braking system at the tail end too. An active rear spoiler adjusts its angle depending on the vehicle speed and attitude, for an optimised combination of drag or downforce.
Cabin comfort benefits are most obvious from about 50km/h, when the breeze would normally start to disturb occupants, up to speeds around the 110km/h mark when the sophisticated solution starts to lose the battle against simple physics.