The convertible version of the two-seater 4C gets the same enhanced equipment offered with the coupé, including an upgraded stereo, increased leather interior trim on the glovebox, luxury floor mats and a bespoke car cover. It also comes with a carbonfibre windscreen frame and more wheel options.
The headlights, which feature a plastic cover rather than a series of open spotlights, are closer to those of the 4C concept than the original coupé. The same headlights are now available as an option on the coupé. It is also available with cruise control and rear parking sensors as no-cost options.
The key element differentiating the 4C Spider from the 4C Coupé launched in 2013 is its removable roof. It will initially be available as a soft, stowable canvas arrangement - as hinted at on the concept - although an optional carbonfibre hard-top is set to become available after UK sales begin in mid-2015, according to Alfa officials.
The 4C Spider also receives a carbonfibre panel that covers the rollover bar behind the cabin, unique single-lens headlights and a new range of alloy wheels, which measure 17in in diameter up front and 18in at the rear.
In a move that has kept the weight gain down to just 10kg (at 1128kg) while retaining a level of rigidity described as being similar to that of the 4C Coupé, the 4C Spider has a carbonfibre windscreen frame that is bonded and bolted to its carbonfibre monocoque chassis.
The glass for both the windscreen and side windows is described as being 10% thinner than that on the 4C.
Additionally, Alfa Romeo has endowed its new model with a newly designed aluminium rollover bar that provides mounting points for the 4C Spider’s unique engine lid, plus a beefed-up strut brace within the engine compartment.
Power comes from the same mid-mounted turbocharged 1.7-litre four-cylinder engine used by the 4C Coupé. Running continuously variable valve timing, it delivers 237bhp at 6000rpm and provides the 4C Spider with a power-to-weight ratio of 210bhp per tonne. Torque swells to a peak of 258lb ft of torque between 2100 and 3750rpm.
Alongside the standard and racing exhausts already available on the 4C, the 4C Spider also comes with an optional lightweight Akrapovic exhaust that uses asymmetrical mufflers, a dual-mode valve system with a link pipe to reduce cabin drone and two centre-mounted tailpipes.
Drive is channelled through Alfa Romeo’s six-speed dual-clutch automatic gearbox which offers the driver the choice of All Weather, Natural, Dynamic and Race driving modes, the latter allowing the engagement of a launch control system for maximum off-the-line acceleration.
Alfa Romeo claims the 4C Spider is capable of accelerating from 0-62mph in just 4.5sec, marginally slower than the 4C Coupé's time.
The 4C Spider will be assembled alongside the 4C Coupé by Alfa Romeo sister company Maserati in Modena, Italy. Production details are yet to be revealed, although officials say volume will be similar to that of the fixed-roof variant at around 3500 units per year.
Speaking at the unveiling of the 4C Spider, Alfa's US boss, Reid Bigland, said: "After a 20-year absence, what gives us the confidence to return is the strength of our past, present and future. Our commitment to the brand is unprecedented. By the end of 2015 we'll have more than 1000 engineers dedicated solely to Alfa. We are led by two ex-Ferrari managers. We are on track for success.