Less than 2 days since the chequered flag fell on the British Grand Prix and they are already back in action at Hockenheim.
Like the Silverstone test, this is a pre-Grand Prix test and so it has extra importance. It's the chance to hone the car and dial it into the circuit.
It's been two years since we raced at Hockenheim and so there will be plenty to do as the teams work out how best to set up their car.
Hamilton topped the timesheets during morning session with a 1:15.550 after 36 laps. The afternoon session will start at 14:00 and finishes at 18:00.
These are the morning test times:
1 HAM 1:15.550 36
2 ROS 1:16.099 35
3 SUT 1:16.516 43
4 HEI 1:16.593 30
5 PIQ 1:16.856 43
6 RAI 1:16.970 17
7 BOU 1:17.135 43
8 COU 1:17.361 25
9 KOB 1:18.118 29
10 WUR 1:18.798 29
Some clearly visible aero-updates are Mclaren's shark-fin engine cover.
Honda also came with new barge boards and wheel fairings.