MANY open-top cars are built to look good above all else - and in Australia, their shallow good looks seem wasted.

They are missing the roof structure that gives a car body its integrity and often therefore wobble like jelly on our bumpy roads and almost invariably it’s too hot, too cold or too polluted to enjoy open-sky motoring.

Yet for the new Audi TT Roadster 2.0 TFSI and 3.2 V6 quattro, the lustre goes far deeper than just the shiny paintwork. These cars have been engineered with real agility and performance, and are a measurable improvement on their predecessors.

The TT Roadster is one of the most appealing and unique roadster designs on the market.

Continuing the Bauhaus design themes of the first TT, the new TT Roadster has become sufficiently more polished and sharpened, and absorbs the requirement of the new Audi corporate nose well.

The smooth appeal flows to the inside, where the TT looks good and is bigger than before. The standard flat-bottom steering wheel is pleasant to grip and if you’re using lots of steering lock quickly, it’s an excellent guide for measuring how much you’re turning.

The previous TT Roadster was first sold only in a high state of tune - the 165kW engine - with a manual transmission only, but ended its run with a lower-output engine and automatic only. So two pedals only is where Audi sees TT-R demand staying - it discovered the requests for manual transmission are simply too sparse.

On that basis, you may think the TT Roadster is just another shallow, open-top show off.

Well, you’d be wrong.

Fire up the TT Roadster 2.0 TFSI and you can immediately sense that there’s a hard-edged four-cylinder just a firewall away. It’s the same excellent direct-injection engine shared with Volkswagens and Audis such as the Golf GTI and Audi A3.

Nothing is lost in translation to the TT Roadster, with full throttle upshifts one of the most rewarding experiences - the ‘automatic’ manual transmission (called DSG in Volkswagens, and S-tronic in Audis) cuts ignition during such upshifts and the resulting exhaust popping sounds great, as does the raw, guttural howl from the engine as it reaches for peak revs.

For those who prefer something smoother and more civilized, there is the 3.2 V6. It is more powerful and ultimately quicker, but it doesn’t give the whip-cracking response to throttle inputs that the 2.0 TFSI does. Yet it sounds great, with a rich baritone V6 growl as you rev it.

The dual-clutch six-speed auto transmission has paddle-shifters and is a pretty sophisticated transmission. When on the move, it smoothly selects the right gear and gets the engine cooking just when you need it to - and the upshifts are as smooth as they can be spectacular in the TFSI.

The only discordant aspect to this transmission is in low-speed manouvres, where getting the right amount of response can be haphazard. We wouldn’t want to reverse uphill on a winding driveway too often with S-tronic.

The TT Roadster handles well, with plenty of grip and with acceptable balance, but the TFSI reminds you that the front wheels are not ideal for translating 147kW to acceleration when climbing a bumpy, winding pass.

The optional Audi Magnetic Ride dampers fitted to the test cars made a difference to the way the suspension reacted to bumps, but you would have to really be passionate about a car’s handling to justify the $3000 over the already good standard suspension.

The fabric roof’s one-button operation is the very least you’d expect of a car like this, but the fact it can be operated at up to 30km/h is a bonus.

The mesh wind deflector does a good job of helping to reduce unwanted wind buffeting, and when the roof is closed only a whisper of wind rustle makes its way through the fabric. Audi’s claim that the body is 120 percent more rigid rings true - there is no body flexing going on.

The boot space is shallow but long enough to store a weekend’s luggage for two, and there is an optional port for long loads. There is also a small storage shelf behind the seats.

The TT Roadster may have the shallow and often impractical fashion appeal of open-top motoring, but for those drivers wanting to delve deeper there is real substance to this car.

Yet is the fun-in-the-sun Roadster really worth the $4k-$5k premium over the equally capable TT Coupe? Don’t ask us - ask your skin specialist.