Yes, resurrecting an old thread but I ran into this problem after buying a used '07 Sport and found Plast-X to be the solution. Bear with me, others haven't had luck with that product but this is how I used it and it worked well.
First, use something really soft to apply the Plast-X, like the old t-shirt remnant at left in the pic. To remove the Plast-X and polish the plastic, it's critical to use a tight-weave microfiber cloth such as the eyeglass polishing cloth shown here. Walmart probably has them and any place like Pearle Vision or Lenscrafters does for sure. They'll usually give you one.
Also important is a note in the Plast-X directions I almost missed - you have to
remove it before it dries. That's the opposite from most other polishes and waxes out there so it's easy to get wrong.
Here are my results. Sorry I didn't think to get a 'before' shot but I had the usual swirly scratches that come from car wash people and my own initial efforts to clean the gauge cluster before I realized it could be such a, well, cluster. ;-)
The plastic isn't perfect but it looks pretty good, especially compared to before. Hope this helps somebody clear up their gauges.