Usually when a car loses its roof it gains both weight and price - but if there is one brand that can turn a coupé into a convertible and have it come out 10kg lighter and at the same price, it's Lotus.

That's exactly what it has done with the Exige S Roadster, released this week and available to order from your friendly local Lotus dealer at the same price as the hard-top Exige S - R1.1 million.

So, what do you get for the equivalent of 48 888 Big Macs?

You get the same mid-mounted, 3.5-litre DOHC 24-valve transverse V6 with Harrop HTV 1320 supercharger, delivering 257kW at 7000rpm and 400Nm at 4500rpm to the rear wheels via a six-speed manual 'box, launching from 0-100km/h in four seconds flat and topping out at an electronically limited 233km/h, at a cost of 10.1 litres per 100km .

UNDERSTATED SILHOUETTE

What you don't get are the coupé's front splitter and rear wing, as the Roadster sacrifices a little downforce in order to minimise buffeting in the cockpit - and thanks to the lightweight fabric soft top (“You're only two clicks and a roll away from open-top cruising,” says Lotus) the topless Exige tips the scale at just 1166kg.

To save you the maths, that's a power-to-weight ratio of 220kW per tonne, perilously close to supercar territory - in a car that is actually prettier than its hard-top sibling thanks to its cleaner, more understated silhouette.

Suspension is by double wishbones all round, with front and rear anti-roll bars, Bilstein high-performance gas dampers and Eibach coaxial springs, while braking is entrusted to AP-Racing four-piston callipers with ventilated and cross drilled cast-iron discs.

Lotus founder Colin Chapman once said: “If you make a car more powerful it will go faster in a straight line. If you make it lighter, however, it will go faster everywhere.”

It would seem he was right.