Jul 21, 2013 - 08:58 AM
As you take your foot off of the accelerator pedal, the car immediately uses the motor to start slowing the car down -- this is regenerative braking (regen). If you take your foot off the accelerator rapidly, it will feel like a down-shift in a manual transmission gas-powered car. You can control how much regen you get by how quickly you take your foot off the accelerator. You can also select "Standard" or "Low" regen from the touchscreen. With the "Low" setting you will get a lower level (less) regen, and less energy will be put back into the batteries. Model S has built-in accelerometers. When the car senses a rapid enough decerlation, it will automatically turn on the brake lights to signal to drivers that you are slowing down. Once you take a little time to get used to the regen, you will probably love this "one-pedal" driving possible with Model S.
Foot on brake pedal is for traditional friction brakes. Model S has very good braking system.
Emergency brake is automatically engaged when put car into "Park" and dis-engaged when take car out of "park".
Jul 21, 2013 - 09:30 AM
I don't have direct knowledge of this, but I would syspect it is a regular hydraulic braking system with 4 channel ABS (that I have tested :). I believe it to be vacuum assisted, as I hear what I believe is a vacuum pump from time to time when I use the brakes.
The e-brake, I believe is integrated into the rear caliper by way of electric motor. Alternatively, it could be an electrically actuated drum-in-hat.