Wrapping things up on this end...
It may not have been too apparent in the videos of driving around, but I was holding the throttle potentiometer in my left hand while doing laps. I had to mount it to the accelerator pedal so that I could finally steer with both hands! I used a cable to tie the pedal to the pot (once mounted) and insured that "flooring it" wouldn't yank the pot off the wall. This setup is a bit more stable and cleaner than it may look from this angle. The cable is fixed on the accelerator arm pretty securely, and goes around the outside of the pedel to keep clear of the driver's foot.
A while back I was mentioning difficulties with the rear brakes, which are electrically-actuated drum brakes. They use 12 V, but applying the full 12 V locks them up immediately (in the manner of an emergency or parking brake). But, I found that applying a variable (lower) voltage would close the brakes more slowly and with less force, so I used a brushed DC motor controller with PWM to fire the motor-driven ball screw actuators that move the drum pads. This is what I did with the brake pedal. Behind the pedal, mounted to the firewall, you can see the Kelly KDS mini brushed controller and the terminal block for all of its inputs and outputs. The RS-232 port there is the interface for programming the controller - which was a must.
The long aluminum arm (actually it's an angle arm, not just a bar - won't bend in the direction of pedal motion) that I have bolted to the pedal face reaches over to the opposite end of the firewall to tie in to another potentiometer which tells the motor controller how much torque to send to the brake pads. The zip tie turned out to be a nice fix with fine adjustment.
One problem with these brakes is that when they are actuated at less that 100%, if you release them (cut power to the ball screw motors), the brakes would not quite open all the way. In order to fix this, I made use of a single pole double throw switch on the pot box, which you can see here labeled with the letters SCO. It's a rigid lever snap action switch, and you can see the top of its lever sandwiched between the big pot lever arm and its stop:
When the switch is released (brake pedal depressed), the motor controller sends its power back to the motors, closing the pads up onto the drums. When you release the brake, the snap action switch closes, and a small 5 V power supply kicks power to the motors in the opposite direction, getting them the last bit of the way open. The 5 V supply is only 10 W, but also operates in intermittent current limiting mode, so it kicks once to open the pads and then gives only small pulses until the next time it switches from "off" (which resets its overload protection) to "on." I couldn't be happier with getting around that problem. The SPDT switch is rated for 25 A too, so it'll handle occasional braking and release currents easily (20 A at the max with the brake pedal floored).
That little motor controller is quite powerful. It delivers 12 V at up to 100 A if you let it. The first time I took a lap around the garage and tried the brake pedal, I squealed the back tires as they locked up. I reprogrammed it to limit the "motor speed" to 30% of the maximum, reduced the motor acceleration rate, limited the maximum current, and now the brakes do their thing a lot smoother.
So I guess that this about does it until the generator set is installed. I have a couple of things to figure out in terms of the magnitude of power draw by the accessory system (motor coolant pump, lights, radiator fan, float charging 12 V batteries, etc.), but everything I can think of is basically in place. The car runs, the lights and brakes work, I have regen, the motor has its coolant flowing, and the CD player works. Can't complain.