it seems to me that there is no way to fix n810 holder on the car, because there is no way to mount on the car. Did i miss anything?

The holder is supposed to be attached to Nokia HH-12 http://europe.nokia.com/A4400026 which is sold separately.

I picked up a similar no-name holder with screw holes in correct places from a local cell phone store for half the price.

Theres an adapter you can purchase that connects to the holder and has a suction cup on the other end. It would have made sense for Nokia to include that in the packaging but they didn't. What I did was fabricate a piece of metal that sits in a cubby hole below my CD player/radio head unit, and then the metal piece drops down towards the ash tray. I mounted the car holder to this piece of metal.

You might want to try the mouting clip from proclip usa. They have clips that fit a wide variety of cars, and they have a neat system called the move clip.
http://www.proclipusa.com/moveclips/moveclips.aspx

I got the move clip and a vehicle mount for my '02 Mazda protege 5 for about $50. I used it in conjuction with the vehicle clip that came with the N810. Hope that helps.

http://www.proclipusa.com/vehiclemou...clemounts.aspx

Joe