Index: src/train_cmd.cpp
===================================================================
--- src/train_cmd.cpp	(Revision 14405)
+++ src/train_cmd.cpp	(Arbeitskopie)
@@ -3254,11 +3254,19 @@
 		v->cur_speed = spd = Clamp(v->cur_speed + ((int)spd >> 8), 0, tempmax);
 	}
 
-	if (!(v->direction & 1)) spd = spd * 3 >> 2;
+	/* Scale speed by 3/4. Previously this was only done when the train was facing diagonally and
+	 * would apply to however many moves the train made regardless the of direction actually moved in.
+	 * Now it is always scaled, 256 spd is used to go straight and 192 is used to go diagonally (3/4 256).
+	 * This results in the same effect, but without the error the previous method caused.
+	 *
+	 * The scaling is done in this direction and not by multiplying the amount to be subtracted by 4/3
+	 * so that the leftover speed can be saved in a byte in v->progress.
+	 */
+	int scaled_spd = spd * 3 >> 2;
 
-	spd += v->progress;
-	v->progress = (byte)spd;
-	return (spd >> 8);
+	scaled_spd += v->progress;
+	v->progress = 0; // set later in TrainLocoHandler or TrainController
+	return scaled_spd;
 }
 
 static void TrainEnterStation(Vehicle *v, StationID station)
@@ -4279,21 +4287,24 @@
 		InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, VVW_WIDGET_START_STOP_VEH);
 	}
 
-	if (j == 0) {
+	int adv_spd = (v->direction & 1) ? 192 : 256;
+	if (j < adv_spd) {
 		/* if the vehicle has speed 0, update the last_speed field. */
-		if (v->cur_speed != 0) return;
+		if (v->cur_speed == 0) SetLastSpeed(v, v->cur_speed);
 	} else {
 		TrainCheckIfLineEnds(v);
-
+		/* Loop until the train has finished moving. */
 		do {
+			j -= adv_spd;
 			TrainController(v, NULL, true);
 			CheckTrainCollision(v);
-			if (v->cur_speed <= 0x100)
-				break;
-		} while (--j != 0);
+			/* 192 spd used for going straight, 256 for going diagonally. */
+			adv_spd = (v->direction & 1) ? 192 : 256;
+		} while (j >= adv_spd);
+		SetLastSpeed(v, v->cur_speed);
 	}
 
-	SetLastSpeed(v, v->cur_speed);
+	if (v->progress == 0) v->progress = j;	// Save unused spd for next time, if TrainController didn't set progress
 }