You're blowing down the freeway in your convertible and your speedometer suddenly fails; what can you do? If you're wearing a Breva Génie 03 wristwatch, you stick it out the window and carry on, as the latest in the Breva line is claimed to be the first watch to include a pop-up mechanical speedometer.

In an age of smartphones, a backup speedometer is only a GPS-equipped app away. Even in the antediluvian days of analog watches, there was the tachymeter on the chronograph dial to let you work out your average speed. But a mechanical wristwatch that can directly measure a vehicle's speed was one complication that hadn't been tried – until now.

The Génie 03 is billed by Breva as "the world’s first-ever wristwatch with a functional speedometer." It looks like many other upmarket watches and is a bit on the bulky side, with hours, minutes, and seconds read off in a dial on at the 7 o'clock position, but the standout feature is the large speedometer dial on the upper corner of the case marked out in either km/h or mph.

When the stud at 2 o'clock is pressed, the speedometer pops up 6 mm from the dial, exposing three titanium-alloy Robinson cups. Like a tiny anemometer, these catch the wind and spin the 45-component mechanism to give a velocity reading. The idea is that someone on a bicycle, motorcycle, convertible, speedboat, or other open vehicle can hold the watch into the wind and measure their speed from 20 to 200 km/h (or 10 to 125 mph), which is displayed directly on the speedometer dial.

For timekeeping, the Génie 03 has a 230 component, 34-jewel proprietary mechanical automatic movement that was developed in-house. Powered by a micro rotor engraved with the Breva compass rose, it has a 60-hour reserve and a 4 Hz balance wheel.

All of this is sealed in a titanium G5 case measuring 44.7 mm x 15.7 mm and the front and back are encased in sapphire crystals with anti-reflective coating. The whole thing is water resistant to 30 m (100 ft), and the speedometer is dust resistant when open. The strap is natural rubber with a titanium buckle.

The Génie 03 is available for US$56,800.

View gallery - 4 images