Having objects avoid one another

[hannahapz]

So I've managed to use the distance function to inform me of when my cars get too close to one another, and I've managed to speed up the lead car/slow down the tailing car to simulate realistic driving, but the problem I'm having is with my nested if loops.

# function that has cars move at a trajectory of, in this example, 10 m/s)
def moving_cars():
	global elapsedTime, z, obs_car
	for i, item in enumerate(my_entire_car_list):
		item.add(vizact.move(0, 0, 10)

# function ensures cars adjust speeds if they get within a certain distance of one another (lead car speed up and tail slows)			
def track_A_moving_cars():
	global track_A, track_B, track_C
	for i in range(len(track_A)):
		for a in track_A[i+1:]:
			if vizmat.Distance(track_A[i].getPosition(), a.getPosition()) < 30.0:
				if track_A[i].getPosition()[2] < a.getPosition()[2]:
					a.add(vizact.move(0, 0, 3, 1), 0)
					track_A[i].add(vizact.move(0, 0, -10, 2), 1)
					
				elif track_A[i].getPosition()[2] > a.getPosition()[2]:
					a.add(vizact.move(0, 0, -10, 2), 2)
					track_A[i].add(vizact.move(0, 0, 3, 1), 3)

EXAMPLE OF MY PROBLEM: targeted tail car will slow down, then resume regular speed, slow down again, resume regular speed, etc. I'm assuming this is because o fmy nested if within nested for loop. I've set the function to run every frame. How do I restart the function?

Any help would be greatly appreciated.