How to tell when VDC works!
Okay, this is only for the terminally curious or trivial-minded, but since a few people have mentioned they can't tell when VDC operates, try this:
Select the AM band on your radio (you almost certainly won't have done this before, so it will be an interesting exercise in itself). Set it to a frequency down the bottom of the band, with no actual station on it - try around 530. You should now be hearing crackly static.
Now go and drive your 147 in the manner for which it was intended. Voila! Whenever the VDC activates your radio will make an annoying high-pitched buzz.
And no, this isn't sad. Sad is when you don't lose interest after 2 minutes, and keep doing it all the time...
(This might work for ABS and/or traction control as well. I haven't been bothered to find out yet!)