It should be possible to get every driver. But Ferrari and Mercedes are hard to get. Easy are Lotus, Red Bull, Toro Rosso and McLaren. The other teams aren't fast in responding to fanmail, but it might work.
Congrats on your success!

I really need stamps from

-USA
-Netherlands
-Belgium
-Denmark
-Italy
-Portugal

I'll give you german stamps for these stamps, if you want to trade PM me.

Is his address still up-to-date?

http://www.fanmail.biz/50237.html

Does anyone know, if Joe Cole signs via West Ham United?

I got a dedicated Valbuena autograph last year by writing a letter to the address in database.
But I never got a reply from Gignac

Today I also got a response of Gerard Deulofeu. I sent LOR and SAE to: Gerard Deulofeu Everton FC Goodison Park Liverpool, L4 4EL UK and got a photo with a PP after one month. Photo: http://www.facebook.com/photo.php?fbid=674134425978970&set=a.638583699534043.1073741833.630378310354582&type=...

Today I got the autograph of César Azpilicueta. I sent LOR, SASE and 2 photos to: César Azpilicueta Chelsea F.C. Stamford Bridge Fulham Road London, SW6 1HS UK and got my photos signed along with a signed club card after 2 weeks. Photo 1: http://www.facebook.com/photo.php?fbid=674134375978975&...

On Thursday I received the autographs of Lukas Podolski, Mario Götze and Manuel Neuer. I sent LOR and SASE to the headquarter of the DFB (German football association) and got signed club cards after one week. In my opinion it's a great success! Photo 1: http://www.facebook.com/photo.php?fbid=672303...

On Monday I got the autograph of Steven Gerrard. I sent two photos, LOR and SASE to his private address and got my pictures signed back after 10 days. I'm really happy about this because I wanted his autograph since one year. If you are interested in the address PM me. Photo 1: http://www.facebook.c...

Exactly one week ago I get the autograph of the German football player Sami Khedira. I sent one photo, LOR and SASE to a private address and got my photo back signed along with a club card of the german team after two weeks. I'm really happy about this success because he is my favourite football pla...