Re: Blank button next to DSTC? (samkell)
Couple of things...
There are two buttons, and they're not identical. The one on the right is a little smaller, and has a more rounded lower curve.
The DSTC function is only there on earlier years, and only on DSTC-equipped cars. AWD cars without DSTC have a blank, and FWD cars get an STC switch. Later years are all blank, since the DSTC function was moved to the stalk.
The C70 puts the convertible top function on the right. Park sensors, I'm not sure but it makes sense there too. Most other Volvos have a button for those.
Someone here made a clever use of the right-side blank, they drilled it out and put in a stereo jack for an iPod input. There was a picture somewhere.
Tom.