Matt-Melbourne

This almost perfectly describes my issue too. Noise is 1900-2200rpm regardless of gear (mine's a manual vRS, but I've confirmed it's independent of the windscreen resonator), and is substantially worse when it's cold outside. Which suggests it relates to something that warms up. I propped mine up on a jack (need to get some axle stands) and poked and prodded at the heat shield/undertray area beneath the driver; they've got these weird one-way clips but all seemed in place; I am pretty much convinced there's something buzzing under there. At one point I packed some vulcanised rubber I had I think between the heat shield and the body which definitely reduced how often the buzz showed up, but of course, the next time I had it serviced and mentioned that there was a buzz which I suspected was the heat shield, the mechanic cleared that out and checked all the clips...and the buzz returned. So, next step for me is to buy some axle stands, possibly a hydraulic jack, and some more vulcanised rubber, which I'll wrap in some tin foil and pack out the heat shield with; and with thanks to your input, I'll check the various lines going nearby as well. And then I won't mention it to the mechanic. Or I will, and tell him to leave it. Anyway, I DO need to make sure this packing work doesn't result in anything melting, particularly on to anything hot, as I generally prefer my car not on fire, but let's see what we can learn.