Why Mercedes' radical sidepods are testing's biggest talking point

SAKHIR, Bahrain -- In the space of Formula One's two preseason tests, Mercedes has presented two very different versions of its new car. When the W13 left Barcelona after the first test it looked relatively conventional. When it emerged again in Bahrain for the second test it looked genuinely revolutionary.

The changes, which were mainly focused on the shape of the car's sidepods, have not gone unnoticed by rival teams, leading to questions about the Mercedes' legality after just one day of running.

Within two hours of the updated car leaving the garage for the first time on Thursday morning, Red Bull team boss Christian Horner was quoted by Auto Motor Und Sport, saying: "Mercedes have gone a…