You know, I think this is a problem for a lot of folks who try products and claim they don't work. I think there is a point where the cladding gets so faded that no product can bring out the original dark color of the cladding. So, if your VX's cladding is not to that point yet, then I would said you are good to go. I think sun is your cladding's worst enemy, but if you use some of the protectant type products (like Trim Shine) I think this will also help prevent further sun damage. I park outside at work for 9 hours a day, and the relentless Nevada sun beats on my VX all day, and my cladding still shines up nicely.
And on a similar note, get a sun shade for your front window, and tint the rest out. I have seen some terrible sun damaged dash boards, steering wheels and leather seats. These materials WILL deteriorate and deteriorate fast if not cared for and protected.
The real question is, what can be done about faded hood inserts? Mine is getting a little light...
Bart