I made these AI lines using Racer v0.5.3 beta 2.0 with the following AI settings in the racer.ini:

ai
{
  ; Thinking rate (ms per step)
  ;time_per_update=1
  time_per_update=20
  ; Looking ahead; velocity*lookahead_factor is the #meters the AI
  ; looks ahead (targeting)
  lookahead_factor=0.02
  ; Minimal lookahead distance; too smooth out steering at low speed
  lookahead_offset=1
  ; Steering response; frequency (lower=slower response, high=fast steering)
  ; Higher values reduce driver induced oscillation it seems.
  steering_frequency=100
  ; Throttle/brake response
  throttle_frequency=2
  ; Line adjustment factor; the higher, the more the car is pulled towards
  ; the driving line
  line_adjust=0.0
  ; Line adjust minimal distance; race distance to be completed before
  ; line adjusting starts
  line_adjust_distance=0.0
  ; Focus on AI car when it appears? (testing AI going around other cars)
  focus=0
  ; Load AI lines at all?
  load_ai_lines=1
  ; Drive alongside player car? (matches velocity to stay near)
  ; Only works with car0=player, car1=AI
  drive_alongside=0
  ; Ignore other cars entirely?
  ignore_cars=0
  ; Velocity scale (global AI performance)
  scale_velocity=1.0
  ; Target U correction speed (default 1.0; lower is slower)
  target_u_correct=1.0
  ; Target smoothing to avoid jerky steering
  target_smd
  {
    mass=1
    k=40
    ; Keep damping close to optimal; sqrt(k)
    damping=4
    maxdist=10
  }
  ; Acceleration smoothing using PID controller
  pid_accelerate
  {
    proportional=-15
    ;proportional=-0.3
    derivative=0.01
    integral=0
  }
  pid_steering
  {
    proportional=75
    derivative=0
    integral=0
  }
}
