Technical cinquecento sporting slight rumble when setting off??

[Grog 18]

Hi there,

I was just wondering, this fiat cinquecento sporting rumbles when i set off, it has no problems what so ever, very well kept and not ragged arround! does anyone know why it rumbles when i set off?? and if its a problem?

 

[Italian Coke Can]

Gear box mount has fallen down / broken slightly. Mount at the back of the engine under the passenger footwell.