ManMan Chui

evening , i have currently covered around 7500 miles since march in my 1.4 t and gradually i have noticed left front metallic rattling under acceleration around the 1.5-2k rpm D5 & D7 gears range over the last few months，and I can only hear it when the windows is down and the sound reflects back in the car,according to my testing , they'll never be able to replicate it in the workshop. The rattle only comes in when the engine is under load, (i.e. the car is moving and accelerating), but is not evident when you gun the engine when stationary

Mine sounds like a marble in a can being shaken about
would like to know if anyone else is hearing this noise ?