Nor Cal Mike
Before you do all that rewiring, consider this. Apply steady voltage to one lane, perhaps the lane that is on the outside of the hairpin turn and use tape to cover one side of the braid on that lane where you want a car to slow down. It will take awhile to figure out where to block the power and how long the 'dead' sections should be, but it can work. You may need to lower the max voltage so cars don't alternate between full and no speed. If you reduce the max speed for your lane too, you can create a pretty equal setup without major changes.
I did this with strips of duct tape on my track so my 5 year old grandson could have a car to practice against. He'd start behind it and have to drive really well without any accidents for many laps to catch the ghost car. The key was having a low voltage power source and I think I ended up using a recycled wall wart type transformer from a rechargeable screwdriver that had an output of around 6 volts. It was plenty powerful enough for 2 cars and you still had to drive the car to stay on the track. Anything that slows slot cars down and still requires driving skills adds realism in my book.
Slothead