diff --git a/y2019/control_loops/drivetrain/event_loop_localizer.h b/y2019/control_loops/drivetrain/event_loop_localizer.h
index aaf377c..9207ec1 100644
--- a/y2019/control_loops/drivetrain/event_loop_localizer.h
+++ b/y2019/control_loops/drivetrain/event_loop_localizer.h
@@ -35,15 +35,15 @@
 
   void Reset(const Localizer::State &state);
   void ResetPosition(double x, double y, double theta) override {
+    // When we reset the state, we want to keep the encoder positions intact, so
+    // we copy from the original state and reset everything else.
     Localizer::State new_state = localizer_.X_hat();
     new_state.x() = x;
     new_state.y() = y;
     new_state(2, 0) = theta;
+    // Velocity terms.
     new_state(4, 0) = 0.0;
     new_state(6, 0) = 0.0;
-    new_state(7, 0) = 0.0;
-    new_state(8, 0) = 0.0;
-    new_state(9, 0) = 0.0;
     Reset(new_state);
   }
 
@@ -64,12 +64,8 @@
   double right_velocity() const override {
     return localizer_.X_hat(StateIdx::kRightVelocity);
   }
-  double left_voltage_error() const override {
-    return localizer_.X_hat(StateIdx::kLeftVoltageError);
-  }
-  double right_voltage_error() const override {
-    return localizer_.X_hat(StateIdx::kRightVoltageError);
-  }
+  double left_voltage_error() const override { return 0.0; }
+  double right_voltage_error() const override { return 0.0; }
 
   TargetSelector *target_selector() override {
     return &target_selector_;
diff --git a/y2019/control_loops/drivetrain/localized_drivetrain_test.cc b/y2019/control_loops/drivetrain/localized_drivetrain_test.cc
index 8a65170..a3bf9a4 100644
--- a/y2019/control_loops/drivetrain/localized_drivetrain_test.cc
+++ b/y2019/control_loops/drivetrain/localized_drivetrain_test.cc
@@ -67,7 +67,7 @@
   void SetStartingPosition(const Eigen::Matrix<double, 3, 1> &xytheta) {
     *drivetrain_motor_plant_.mutable_state() << xytheta.x(), xytheta.y(),
         xytheta(2, 0), 0.0, 0.0;
-    Eigen::Matrix<double, 10, 1> localizer_state;
+    Eigen::Matrix<double, 7, 1> localizer_state;
     localizer_state.setZero();
     localizer_state.block<3, 1>(0, 0) = xytheta;
     localizer_.Reset(localizer_state);
@@ -296,7 +296,7 @@
       .Send();
   RunForTime(chrono::seconds(3));
   VerifyNearGoal();
-  VerifyEstimatorAccurate(1e-5);
+  VerifyEstimatorAccurate(1e-4);
 }
 
 namespace {
diff --git a/y2019/control_loops/drivetrain/localizer_test.cc b/y2019/control_loops/drivetrain/localizer_test.cc
index 8b6f7ed..f062234 100644
--- a/y2019/control_loops/drivetrain/localizer_test.cc
+++ b/y2019/control_loops/drivetrain/localizer_test.cc
@@ -399,7 +399,7 @@
     U(1, 0) = ::std::max(::std::min(U(1, 0), 12.0), -12.0);
 
     state = ::frc971::control_loops::RungeKuttaU(
-        [this](const ::Eigen::Matrix<double, 10, 1> &X,
+        [this](const ::Eigen::Matrix<double, 7, 1> &X,
                const ::Eigen::Matrix<double, 2, 1> &U) { return DiffEq(X, U); },
         state, U,
         ::std::chrono::duration_cast<::std::chrono::duration<double>>(
@@ -418,7 +418,7 @@
                            ::std::pow(state(StateIdx::kRightVelocity, 0), 2)) /
                    3.0);
       TestLocalizer::State disturbance;
-      disturbance << 0.02, 0.02, 0.001, 0.03, 0.02, 0.0, 0.0, 0.0, 0.0, 0.0;
+      disturbance << 0.02, 0.02, 0.001, 0.03, 0.02, 0.0, 0.0;
       disturbance *= disturbance_scale;
       state += disturbance;
     }
@@ -498,11 +498,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/false,
             /*disturb=*/false,
@@ -514,11 +512,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -4.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -4.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.0, -4.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -4.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/false,
             /*disturb=*/false,
@@ -529,11 +525,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/true,
             /*disturb=*/false,
@@ -544,26 +538,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.1, -5.1, -0.01, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0, 0.0)
-                .finished(),
-            /*noisify=*/false,
-            /*disturb=*/false,
-            /*estimate_tolerance=*/1e-4,
-            /*goal_tolerance=*/2e-2,
-        }),
-        // Repeats perfect scenario, but add voltage + angular errors:
-        LocalizerTestParams({
-            /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
-            /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0,
-             0.5, 0.02)
-                .finished(),
-            (TestLocalizer::State() << 0.1, -5.1, -0.01, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0, 0.0)
+            (TestLocalizer::State() << 0.1, -5.1, -0.01, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/false,
             /*disturb=*/false,
@@ -574,11 +551,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/false,
             /*disturb=*/true,
@@ -589,16 +564,14 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.0, 3.0, 3.0, 0.0, 1.0, 1.0}},
             /*control_pts_y=*/{{-5.0, -5.0, 2.0, 2.0, 2.0, 3.0}},
-            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.0, -5.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.1, -5.1, 0.03, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.1, -5.1, 0.03, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/true,
             /*disturb=*/true,
             /*estimate_tolerance=*/0.15,
-            /*goal_tolerance=*/0.5,
+            /*goal_tolerance=*/0.8,
         }),
         // Try another spline, just in case the one I was using is special for
         // some reason; this path will also go straight up to a target, to
@@ -606,11 +579,9 @@
         LocalizerTestParams({
             /*control_pts_x=*/{{0.5, 3.5, 4.0, 8.0, 11.0, 10.2}},
             /*control_pts_y=*/{{1.0, 1.0, -3.0, -2.0, -3.5, -3.65}},
-            (TestLocalizer::State() << 0.6, 1.01, 0.01, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.6, 1.01, 0.01, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
-            (TestLocalizer::State() << 0.5, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
-             0.0, 0.0)
+            (TestLocalizer::State() << 0.5, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0)
                 .finished(),
             /*noisify=*/true,
             /*disturb=*/false,