Free Breitling watch

This Swiss Breitling watch costs $290,000, but you can have it for free.

Only one problem: you have to buy one of 100 limited-edition Bentley Continental ISR Supersports convertibles (pictured right) costing $553,000 in Australia.

That's $42,000 more than the "standard" Supersports convertible, so the buyer potentially saves $250,000 on the value of the car and watch.

Bentley Motors regional manager Ed Striebig says they have not yet received an order for an ISR, "but the order books are open".

"We've been about 1 per cent of our worldwide sales, so on that basis, we should expect a car to come to these shores," he says.

The car and watch are inspired by four-time world rally champion Juha Kankkunen's 330.695km/h world-record-breaking run this year on the perilous frozen Baltic Sea, off the coast of Finland. He was driving an all-wheel drive, biofuel-powered 6-litre, 12-cylinder Continental Supersports convertible when he broke his previous ice speed record of 321.6km/h set in 2007 in the Continental GT.

The ISR (Ice Speed Record) model is up 7kW to 470kW on the convertible driven by Kankkunen and is the most potent Bentley yet, reaching 100km/h in 3.8 seconds and 160km/h in 9.5 seconds.

Power is transferred between the front and rear axles automatically via a Torsen center differential and it features massive 419mm carbon ceramic rotors up front and 355mm at the rear. It sits on 275mm wide tyres on 20-inch wheels.

The ISR comes in three special exterior colours - Beluga, Quartzite, and Arctica White - with a dark grey metallic soft top.

The 100 self-winding watches and Bentley convertibles have similar design cues such as red detailing, carbonfibre fascia and knurled finish on the buttons. Of course, the signature Breitling dashboard clock also has a red accent.

And both the car and watch feature the same engraved number.

Bentley Continental ISR Supersports convertible

Price: $553,000
Engine: 6-litre twin-turbocharged W12, 471kW/800Nm
Transmission: 6-speed automatic
Performance: 0-100km/h in 3.8 seconds, top speed 525km/h
Dimensions: 4804mm (L), 2194mm (W), 1388mm (H), 2745mm (WB) Kerb weight: 2395kg
Tyres: 275/35 R20
Economy: 16.7L/100km (combined)
CO2: 388g/km.