McLaren have come to Germany with extensive updates and it paid off in the wet first practice session:

Pos Driver Team Time Laps
1. Jenson Button McLaren-Mercedes 1m16.595 27
2. Lewis Hamilton McLaren-Mercedes 1m17.093s + 0.498 22
3. Fernando Alonso Ferrari 1m17.370s + 0.775 21
4. Michael Schumacher Mercedes 1m17.382s + 0.787 20
5. Sergio Perez Sauber-Ferrari 1m17.413s + 0.818 28
6. Nico Hulkenberg Force India-Mercedes 1m17.599s + 1.004 17
7. Nico Rosberg Mercedes 1m17.915s + 1.320 27
8. Felipe Massa Ferrari 1m17.995s + 1.400 22
9. Pastor Maldonado Williams-Renault 1m18.020s + 1.425 20
10. Romain Grosjean Lotus-Renault 1m18.130s + 1.535 21
11. Kamui Kobayashi Sauber-Ferrari 1m18.226s + 1.631 22
12. Sebastian Vettel Red Bull-Renault 1m18.339s + 1.744 21
13. Valtteri Bottas Williams-Renault 1m18.422s + 1.827 28
14. Daniel Ricciardo Toro Rosso-Ferrari 1m18.709s + 2.114 30
15. Kimi Raikkonen Lotus-Renault 1m18.831s + 2.236 14
16. Jules Bianchi Force India-Mercedes 1m18.972s + 2.377 21
17. Jean-Eric Vergne Toro Rosso-Ferrari 1m19.039s + 2.444 34
18. Vitaly Petrov Caterham-Renault 1m19.674s + 3.079 24
19. Heikki Kovalainen Caterham-Renault 1m19.963s + 3.368 24
20. Mark Webber Red Bull-Renault 1m20.122s + 3.527 27
21. Charles Pic Marussia-Cosworth 1m20.169s + 3.574 20
22. Timo Glock Marussia-Cosworth 1m20.539s + 3.944 18
23. Pedro de la Rosa HRT-Cosworth 1m21.138s + 4.543 24
24. Dani Clos HRT-Cosworth 1m21.740s + 5.145 27
Jenson Button quickest in rain-hit first practice for the German Grand Prix - F1 news - AUTOSPORT.com