Audi A3 roof hits new heights

AUDI’S all-new A3 Cabriolet will be raising the roof in a very different manner than before when local sales commence in the third quarter of next year.

Departing from the old-style ‘Z’ fold canvas top, the second-generation four-seater convertible adopts a fresh ‘K’ fold mechanism with a number of added benefits.

Said to be lighter and less space-intrusive when folded down, the new top takes less time to open and close (18 seconds) and can be done so when the car is moving up to 50km/h.

The 2015 A3 Cabriolet also debuts the Volkswagen Group’s new ‘MQB Convertible’ platform that is expected to underpin the next-generation VW Golf Cabriolet as well as the slow-selling Eos’ replacement.

According to the man in charge of the Volkswagen Group’s Technical Development of Convertible Tops, Mario Weiland, the decision was taken early on in the 8V-series A3’s development to combine elements of the MQB hatch and sedan platform.

The aim with the extra length wheelbase was to add extra passenger-compartment as well as cargo-carrying space.

“Going with the sedan platform helped with the possibility of a more beautiful convertible,” he told GoAuto at the launch of the A3 Cabriolet in Monaco earlier this month.

“We now have the right base. It is more of a premium car, and a real difference compared to the Golf Cabriolet.

“Also, it improves rear set legroom and boot space – which is important in this class.”

Audi commenced A3 Cabriolet work in 2010, some time after development of the hatch and sedan versions commenced.

Both the BMW 1 Series Convertible and the A5 Convertible served as benchmarks, particularly as far as the roof style was concerned.

“Our research shows that our customers think the A5 Convertible has the perfect shape with its tonneau cover design, with its longer trunk,” Mr Weiland said.

“So this is a decision we made very early on in the A3 Cabriolet development – to emulate the K-fold top from the A5 Convertible. The old A3, TT and Golf Cabriolet still use the Z-fold system.”

The more compact folding roof design, which is significantly lighter on its own – using magnesium and aluminium in the frame structure, as well as cloth for the roof – did dictate some other changes to the vehicle.

These included a relatively shallow rear window shape, as well as the implementation of flush-folding headrests, for a cleaner and more uncluttered silhouette when the roof is in situ.

However, the flipside is a whole lot more complication as far as the roof folding mechanism is concerned, since an extra four hydraulic lifters are necessary to open and shut the body-coloured tonneau that the covers the roof.

The abolition of the previous A3 Cabriolet’s rollover hoops for a pair of poles that deploy in milliseconds also added weight and further complexity, particularly as they have been engineered to support several times the weight of an upturned vehicle.

Plus, the associated additional electrics and hydraulics made packaging all those items a real challenge, according to Mr Weiland.

“The biggest challenge was packaging the roof within the boot area, and yet still getting it to look just like an A5 Convertible,” he revealed.

“Even the new type of rollover protection system challenged us with its packaging problems.”

To help offset the loss of structural rigidity, Audi’s engineers swapped the previously plastic cover underneath the engine bay for a load-bearing alloy plate, which also helps with improving airflow beneath the vehicle.

Various parts of the body – including the dashboard and windscreen posts – have also been beefed up.

“The MQB Convertible platform is much stiffer than the old PQ45 platform of the old Audi A3 Cabriolet,” Mr Weiland said.

While nobody at Audi would reveal any details about what the next models to use the new architecture are, we understand that the Mk7 version of the Golf Cabriolet will surface globally sometime in 2016.

A larger and more luxurious vehicle also based on this hardware – though perhaps more closely related to the next-generation B9 Passat due later in 2014 – is believed to form the basis of the Eos replacement.

Meanwhile the A3 Cabriolet and its equally fresh A3 Sedan are both produced at the Gyor plant in Hungary, alongside the TT as well as up to 90 per cent of all Audi engines.