[Land-speed] Slip Indicator

[Elon]

Keith I know you are going through de-tox so absent mindedness is
acceptable. A couple of weeks ago I asked a question about your slip
indicator in the Camaro but you never responded. You mentioned it during one
of the "otto" discourses. You don't have to get into the electronics but how
did it work?  Was it an of-the-shelf device or did someone make it for you?
I'm not talking about the slew-rate traction controls that are available. I
want driver control, not computer control.  -Elon