Slice the roof off a dramatic looking coupe to create a roadster and a quick analysis of the gains and losses will read something like: greater exclusivity, bigger pricetag, less load space, more weight, slightly less performance.
In the case of the Audi TT Roadster a couple of other things happen as well. A rather optimistic two-plus-two cabin becomes a dedicated two-seater and there's even more of the TT's signature polished metal detailing thanks to the open car's twin roll-over hoops.
The TT Roadster arrived in New Zealand mid-year, about 12 months after the launch of the Coupe to provide a second opportunity for Audi's strikingly original sports car to step into the spotlight.
Offering the same turbocharged 132kW front-wheel drive and 165kW Quattro choices as its lidded stablemate, the roadster price premium is $5000. That's very much at the low end of what manufacturers usually charge to recoup the costs of re-engineering the car and adding a power operated soft-top.
It means the Quattro version tested here is $99,900 and a two-wheel drive costs $82,900.
The TT Coupe has one of the most distinctive shapes on the road with a daring blend of retro and modern themes. The roadster is a natural progression sharing the same short and wide stance with a high waistline. Prominent curves, especially over the wheelarches, intersected by crisp cut feature lines is the other key part of the design.
An electrically-operated soft-top provides shelter from the elements. It works swiftly and only the single central locking latch needs to be operated manually. With the roof lowered the clip-in tonneau cover which tidies up the lines of the car can be a little fiddly to fit. And with the roof raised and the cover stowed away it takes up quite a lot of the restricted boot space.
A plastic rear window rather than a glass one is a minor drawback. A clever glass wind-blocker can be electrically raised just behind the seats to reduce buffeting in the cockpit at open road speeds.
It works. You only need to lower the screen for a moment at open road speeds to confirm the difference it makes to turbulence and noise within the cockpit.
Although the low roofline and the high waistline can make the cabin feel a little claustrophobic with the roof raised there is adequate headroom because the height-adjustable driver's seat can be lowered close to the floor.
The driving position is comfortable with firmly bolstered leather seats offering slide, recline and cushion height adjustments. A tilt and telescope steering column fine tunes the driving position.
Rivalling, perhaps surpassing, the exterior of the TT for authenticity of design is the interior.
The architecture combines leather, high quality textured plastics and polished alloy. In particular the twist bezel vent outlets are a work of art and the theme is continued by the alloy door handles, pedals, gearknob and the cast structures which support the fascia and form the lower part of the centre console.
The extra polished metal on show is the satin finish double roll-over bars. They provide a definite talking point of the design and also fill much of what used to be the rear seat passenger space.
Much of the focus in designing an open-topped car centres on minimising the loss of torsional strength which is inevitable when the roof is removed.
The Roadster's sills are made of thicker metal than the Coupe's and its strengthened windscreen frame is double anchored inside the A-posts using tube-in-tube reinforcement where the A-post meets the floor.
A significant weight penalty accompanies the strengthening work. The front-wheel-drive TT Roadster weighs 1310kg (up by 70kg over the Coupe); the Quattro Roadster tips the scales at a hefty 1475kg (up by 80kg).
The extra weight - in effect there's a third passenger on board - blunts acceleration times.
Audi says the front-wheel drive Roadster with its 132kW engine clocks 7.9 seconds for the 0-100km/h sprint compared with 7.5 seconds for the Coupe with the same powertrain.
The more powerful Quattro Roadster with 165kW turbo power is 0.3secs slower to 100km/h than the Quattro Coupe, clocking 6.7 seconds.
Aerodynamics are also affected by the change of body style with the drag coefficient rising from 0.32 to 0.36.
Completing the list of compromises which accompany the choice of a roadster ahead of coupe is reduced luggage capacity. The space needed to stow the soft-top significantly reduces luggage room.
In the front-drive Roadster the 220 litre load capacity is 50 litres smaller than the Coupe's. The soft-top Quattro (which has a less space efficient independent rear suspension) is restricted to just 180 litres (down from 220 litres).
But these are minor inconveniences which convertible enthusiasts accept as pretty much inevitable. They buy the Roadster for its style and exclusivity and the appeal of open air motoring. A few reduced measurements here and there and a few tenths added to the performance figures are unlikely to sway their buying decision.
The reward of open air sports car motoring - from the humblest used import Mazda MX-5 to the most expensive luxury brand convertible - is the ability to turn routine small journeys into a memorable occasion.
In a matter of minutes roadster drivers can leave the worries and stress of the work day in their slipstream. With the TT Quattro Roadster a significant part of the appeal is sheer performance.
The recipe of high-torque turbo power and the six-speed gearbox (it will soon replace the five-speeder on the 132kW model as well) means plenty of accelerative urge and long-legged open road cruising ability.
The 1.8-litre DOHC four cylinder with five-valves per cylinder is a mainstay of VW Group products. In varying states of tune it's used in everything from Skoda Octavias to SEATs as well as VW Golfs and Passats and high-performance Audis like the S3 and A4 1.8T.
Under the TT Quattro's stubby bonnet the motor is turbocharged and twin intercooled to develop 165kW at 5900rpm. Torque plateaus at 280Nm between 2200 and 5500rpm.
The slick-shifting six-speeder uses 2500rpm at 100km/h in top gear and offers the choice of moving down the gearbox to point the tachometer needle at 3000rpm in fifth or 3800rpm in fourth. There's enormous scope for exploiting the torque which dominates the engine's character.
Like most modern turbocharged engines there's only throttle lag if you get caught without enough load on the engine and a couple of gears above where you really need to be. Keep the engine under just a touch of load to keep the turbo spinning and immensely flexible mid-range torque is the prime mover of the TT Roadster. Revving it hard is unnecessary.
The TT sits on a short wheelbase and has a wide track. The suspension - MacPherson struts at the front and a double wishbone arrangement at the rear for Quattro models - is moderately firm and keeps body roll under strict control.
Explore the limits in some challenging corners and the impression is that grip dominates over agility. The TT will carry good speed through corners accompanied by mild understeer that can make it feel a little nose heavy and it relies on Quattro adhesion and top quality rubber rather than inherent balance.
I drove the TT Roadster not long after testing the Porsche Boxster 2.7. The two German cars are poles apart in how they achieve their cornering performance. The Boxster is all nimbleness, mid-engine balance and naturally-aspirated throttle response to make it direct and supremely adjustable. In contrast sheer grip gets the TT through, and it feels a lot heavier and its responses aren't as sharp.
The TT Roadster is highly capable but not as involving as the Boxster. You're aware the Audi has been developed from a closed car and one that shares underpinnings with a VW Golf. The Boxster is a pure-bred roadster and the extra $20,000 reinforces that.
Continental ContiSport Contact radials in 225//45 ZR17 dimension are fitted to a classic-design six-spoke 17-inch alloy wheel. Continental mightn't be a high profile performance tyre brand in New Zealand but they were well suited to our roads with assured adhesion and low to moderate road roar on coarse chip surfaces.
The NZ specification for the TT Roadster duplicates the Coupe. Standard features of both front-drive and Quattro examples are climate control air-conditioning, leather-upholstered sports seats, a leather-wrapped steering wheel, six speaker audio with six disc CD stacker, power windows and mirrors and a remote central door-locking system with immobiliser and alarm.
Safety items include frontal and side impact airbags, ABS anti-skid brakes with electronic brake force distribution (EBD) and the Electronic Stability Programme (ESP). The front-wheel drive version has traction control but four-wheel drive takes care of that function on the 165kW cars.
The only specification difference between front-wheel drive and Quattro versions - other than the more powerful engine, six-speed gearbox and a larger wheel/tyre combination - is a multi function trip computer on the Quattro.
AutoPoint road test team: CM.