Bentley Claims a 208mph Underwater Speed Record

The new generation of Bentley Continental GT has made an interesting debut ahead of its public reveal at the Goodwood Festival of Speed this weekend, claiming an underwater speed record.

Of course the new fourth-generation car wasn’t literally running underwater, but through a long subsea tunnel. In fact the tunnel itself is a record-holder, with the Ryfylketunnelen in Norway being both the longest undersea road tunnel in the world and the deepest tunnel of any kind on the planet. It carries almost nine miles of the National Route 13, in two directions, and at its lowest point is some 292 metres below sea level.

While traffic through the tunnel is ordinarily restricted to a maximum of 80km/h (50mph), Bentley had other ideas and wanted to see just how fast the new Continental GT could go with its 771hp twin-turbo V8 hybrid powerplants.

It’s not exactly a matter of pinning the throttle to the floor either, as tunnels pose interesting aerodynamic challenges. For example the Eurostar trains which head through the Channel Tunnel have to drop from their 186mph maximum to just 100mph, as there’s no way for the air to escape from the confines of the concrete tube and the air pressure alone could be enough to lift the train off the tracks at higher speeds…

As you’d expect then, Bentley did its homework and employed computational fluid dynamics (CFD) simulations before ever getting the car near the tunnel. Its calculations revealed that, in the confined environment and so far below sea level, the car would experience 11 percent greater aerodynamic drag. More severely, running close to the walls could cause a suction effect, so the Continental GT had to stay as close to the middle of the two-lane road as possible.

Mark Higgins was at the wheel for the record runs, carried out at one o’clock in the morning to minimise traffic disruption, but the Continental GT didn’t need more than a single pass as it hit 208mph (335km/h) on its first try.