Acceleration noise

[Rayz]

Hi guys, I’m new here, I have a 2019 1.0 tsi manual touran with 46k miles.

in first gear and reverse with light acceleration I get a sound, the best way I can describe it is like the Knight Rider Kitt front red light sound (kkhwooowkh).

this sound appears when I release the accelerator, it makes the sound even when in neutral but not as loud when in gear.

Its also only giving 26mpg, this may be down to heavy body for the 1.0 engine but still is very low, 

I have had the clutch and flywheel checked, this is fine and bites where It should be. No flywheel sound, air filter box pipes all secure. 
 

any ideas please. Thanks

[Volkswagen Owners Club]

not sure if it is turbocharged but if so then it is more than likely a hole or split in the pressure side of the turbo or intercooler