diff --git a/src/ground_vehicle.cpp b/src/ground_vehicle.cpp
index 66e5b99..142353f 100644
--- a/src/ground_vehicle.cpp
+++ b/src/ground_vehicle.cpp
@@ -47,8 +47,9 @@ void GroundVehicle<T, Type>::PowerChanged()
 
 	/* If air drag is set to zero (default), the resulting air drag coefficient is dependent on max speed. */
 	if (air_drag_value == 0) {
+		uint16 max_speed = v->GetDisplayMaxSpeed();
 		/* Simplification of the method used in TTDPatch. It uses <= 10 to change more steadily from 128 to 196. */
-		air_drag = (max_track_speed <= 10) ? 192 : max(2048 / max_track_speed, 1);
+		air_drag = (max_speed <= 10) ? 192 : max(2048 / max_speed, 1);
 	} else {
 		/* According to the specs, a value of 0x01 in the air drag property means "no air drag". */
 		air_drag = (air_drag_value == 1) ? 0 : air_drag_value;
diff --git a/src/pathfinder/yapf/yapf_costrail.hpp b/src/pathfinder/yapf/yapf_costrail.hpp
index fe025ee..1de6eba 100644
--- a/src/pathfinder/yapf/yapf_costrail.hpp
+++ b/src/pathfinder/yapf/yapf_costrail.hpp
@@ -466,11 +466,12 @@ no_entry_cost: // jump here at the beginning if the node has no parent (it is th
 			{
 				int min_speed = 0;
 				int max_speed = tf->GetSpeedLimit(&min_speed);
-				if (max_speed < v->max_speed) {
-					extra_cost += YAPF_TILE_LENGTH * (v->max_speed - max_speed) * (4 + tf->m_tiles_skipped) / v->max_speed;
+				int max_veh_speed = v->GetDisplayMaxSpeed();
+				if (max_speed < max_veh_speed) {
+					extra_cost += YAPF_TILE_LENGTH * (max_veh_speed - max_speed) * (4 + tf->m_tiles_skipped) / max_veh_speed;
 				}
-				if (min_speed > v->max_speed) {
-					extra_cost += YAPF_TILE_LENGTH * (min_speed - v->max_speed);
+				if (min_speed > max_veh_speed) {
+					extra_cost += YAPF_TILE_LENGTH * (min_speed - max_veh_speed);
 				}
 			}