My bike rack solution (Saris rack)
This might be a little off topic, but I just wanted to explain the solution I came up with for my P5 bike rack.
About 10 years ago I bought a rooftop system from a company called Saris. I don't know if they still make their roof racks. It's a very nice sliding track system that is sleek and low-profile, and I always thought it looked much better than Thule or Yakima.
When I got my P5, I figured out a way to mount the bike carriers to the stock P5 roof bars. The P5 roof bars are very structurally similar to the Saris bars. Remove the rubber strip on the P5 bars, and there is a channel.
The Saris attachments (bike, ski, etc) fit by sliding them onto the bars. All I did was buy some sturdy brass washers from Home Depot. These help fill in the channel space, since the P5 channel is a little bigger than the Saris channel. Tighten the regular bolts, then "voila".
I have used this setup for 2 summers now. It's sturdy, and it looks just like the rack was made for the car. It's low-profile, but doesn't bother the sunroof. However when you have a bike on the roof, you usually can't open the hatch because the spoiler hits the bike wheel. (It is a full-upright carrier)
The only issue is that it is not easy to take on and off, so I leave it on the whole time in spring in summer. The Saris system lets you slide the attachments on and off, but you can't do this because of the plastic trim pieces on the ends of the P5 bars. So you just leave them on. I have ski carriers too, but skis just go in the trunk, and unfortunately I don't ski much anymore :-(.
One of these days I'll post pictures. I'm kinda happy that I worked out a safe, sturdy, nice-looking solution for about only $2.00 at Home Depot!