Some Informations directly from Rosberg about the Car and testing...
Q: It´s a rumor that the cars are slower... are there lower forces for the driver while driving?
A: "We don´t know by now because we are driving really slowly.
1. We don´t want to show the real potential of the car and it´s aerodynamics and the aerodynamics of the car is really crude. We just want to check the reliability.
2. The tires are hard as stones and we don´t get temperature in them. "
Q: How is it driving the "brake by wire system"? Do you feel confident braking?
A: "It´s complicated to describe. the front is a standard brake. Only the rear is nearly completely braked by the ERS. On high speeds you have plenty of downforce so you have a fully angaged rear brake. It´s like using the handbrake on a normal car.
When slowing down the car, the downforce is lower so you have to release the brake. To set this up is really complicated. The balance between the mechanical front and nearly completely electrical rear brake is key and complicated. At the moment it´s not perfectly adjusted. I don´t know what I´ve written but I hope you´ve understood 
"
thats not 1:1 translation but I´ve translated the content.
For me the key points of his informations are:
- Aerodynamics are primitive at the moment.
- Tires aren´t working
- brake balance isn´t set up properly by now.
with the additional Information that they are running only up to 13krpm I think a 1:23:xxx lap is quite fast.
Compared to the 1:17:8 from Massa on soft tires (3 lap stint) last year.
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