After 2000km our new Passat developed and intermittent rattle from ostensibly the centre front dash. It became more frequent so I took it to the dealers. The first suggestion was that it was a harmonic from the wipers (noting it occurred whether or not the wipers were on). The final solution: a rattle from the e-tag near the rear vision mirror. So far, so good.
The message is to check the e-tag as e-tags apparently often start to rattle. It may stop some costly repairs.