"Finland is when it (the training) all starts again in earnest, " said Hamilton, whose Finnish team-mate Heikki Kovalainen will be testing again in Spain and Portugal this month after the camp in his home country.
Gronholm's Finnish compatriot and team-mate Mikko Hirvonen is fourth with Jan Kopecky in fifth, 2.7 seconds ahead of Citroen's Toni Gardemeister (Citroen) in fifth.
This week, a team of Finnish researchers did what we would have thought was impossible, building an electricity-free computer that's powered by water droplets.
The software was developed six years ago by a team in Finland partly for the Finnish military, to manage the movement of supplies if a road were blown up.