diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index 25be72919c..f4c60c9d1c 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -54,17 +54,17 @@ void Aircraft::UpdateDeltaXY(Direction direction)
 				case FLYING:     x = MKIT(24, 24, -1, -1); break;
 				default:         x = MKIT( 2,  2, -1, -1); break;
 			}
-			this->z_height = 5;
+			this->z_extent = 5;
 			break;
-		case AIR_SHADOW:     this->z_height = 1; x = MKIT(2,  2,  0,  0); break;
-		case AIR_ROTOR:      this->z_height = 1; x = MKIT(2,  2, -1, -1); break;
+		case AIR_SHADOW:     this->z_extent = 1; x = MKIT(2,  2,  0,  0); break;
+		case AIR_ROTOR:      this->z_extent = 1; x = MKIT(2,  2, -1, -1); break;
 	}
 #undef MKIT
 
 	this->x_offs        = GB(x,  0, 8);
 	this->y_offs        = GB(x,  8, 8);
-	this->sprite_width  = GB(x, 16, 8);
-	this->sprite_height = GB(x, 24, 8);
+	this->x_extent      = GB(x, 16, 8);
+	this->y_extent      = GB(x, 24, 8);
 }
 
 
diff --git a/src/disaster_cmd.cpp b/src/disaster_cmd.cpp
index 0482edeaad..097aaf5677 100644
--- a/src/disaster_cmd.cpp
+++ b/src/disaster_cmd.cpp
@@ -1061,7 +1061,7 @@ void DisasterVehicle::UpdateDeltaXY(Direction direction)
 {
 	this->x_offs        = -1;
 	this->y_offs        = -1;
-	this->sprite_width  =  2;
-	this->sprite_height =  2;
-	this->z_height      =  5;
+	this->x_extent      =  2;
+	this->y_extent      =  2;
+	this->z_extent      =  5;
 }
diff --git a/src/oldloader.cpp b/src/oldloader.cpp
index a84cb66fe2..ccd64c3b55 100644
--- a/src/oldloader.cpp
+++ b/src/oldloader.cpp
@@ -1155,8 +1155,8 @@ static const OldChunks vehicle_chunk[] = {
 	OCL_SVAR(  OC_UINT8, Vehicle, z_pos ),
 	OCL_SVAR(  OC_UINT8, Vehicle, direction ),
 	OCL_NULL( 2 ),         ///< x_offs and y_offs, calculated automatically
-	OCL_NULL( 2 ),         ///< sprite_width and sprite_height, calculated automatically
-	OCL_NULL( 1 ),         ///< z_height, calculated automatically
+	OCL_NULL( 2 ),         ///< x_extent and y_extent, calculated automatically
+	OCL_NULL( 1 ),         ///< z_extent, calculated automatically
 
 	OCL_SVAR(  OC_UINT8, Vehicle, owner ),
 	OCL_SVAR(   OC_TILE, Vehicle, tile ),
diff --git a/src/roadveh_cmd.cpp b/src/roadveh_cmd.cpp
index 2314a9aa10..2311287add 100644
--- a/src/roadveh_cmd.cpp
+++ b/src/roadveh_cmd.cpp
@@ -585,9 +585,9 @@ void RoadVehicle::UpdateDeltaXY(Direction direction)
 	uint32 x = _delta_xy_table[direction];
 	this->x_offs        = GB(x,  0, 8);
 	this->y_offs        = GB(x,  8, 8);
-	this->sprite_width  = GB(x, 16, 8);
-	this->sprite_height = GB(x, 24, 8);
-	this->z_height      = 6;
+	this->x_extent      = GB(x, 16, 8);
+	this->y_extent      = GB(x, 24, 8);
+	this->z_extent      = 6;
 }
 
 static void ClearCrashedStation(Vehicle *v)
diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
index ae7bea8b4b..a3e460a295 100644
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -322,9 +322,9 @@ void Ship::UpdateDeltaXY(Direction direction)
 	uint32 x = _delta_xy_table[direction];
 	this->x_offs        = GB(x,  0, 8);
 	this->y_offs        = GB(x,  8, 8);
-	this->sprite_width  = GB(x, 16, 8);
-	this->sprite_height = GB(x, 24, 8);
-	this->z_height      = 6;
+	this->x_extent      = GB(x, 16, 8);
+	this->y_extent      = GB(x, 24, 8);
+	this->z_extent      = 6;
 }
 
 void RecalcShipStuff(Vehicle *v)
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 826861fe47..8bd5c2d8a4 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -1529,9 +1529,9 @@ void Train::UpdateDeltaXY(Direction direction)
 	uint32 x = _delta_xy_table[direction];
 	this->x_offs        = GB(x,  0, 8);
 	this->y_offs        = GB(x,  8, 8);
-	this->sprite_width  = GB(x, 16, 8);
-	this->sprite_height = GB(x, 24, 8);
-	this->z_height      = 6;
+	this->x_extent      = GB(x, 16, 8);
+	this->y_extent      = GB(x, 24, 8);
+	this->z_extent      = 6;
 }
 
 static void UpdateVarsAfterSwap(Vehicle *v)
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index 349ef1b5b6..5602fb7b9b 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -767,7 +767,7 @@ static void DoDrawVehicle(const Vehicle *v)
 	}
 
 	AddSortableSpriteToDraw(image, pal, v->x_pos + v->x_offs, v->y_pos + v->y_offs,
-		v->sprite_width, v->sprite_height, v->z_height, v->z_pos, (v->vehstatus & VS_SHADOW) != 0);
+		v->x_extent, v->y_extent, v->z_extent, v->z_pos, (v->vehstatus & VS_SHADOW) != 0);
 }
 
 void ViewportAddVehicles(DrawPixelInfo *dpi)
@@ -3234,9 +3234,9 @@ void SpecialVehicle::UpdateDeltaXY(Direction direction)
 {
 	this->x_offs        = 0;
 	this->y_offs        = 0;
-	this->sprite_width  = 1;
-	this->sprite_height = 1;
-	this->z_height      = 1;
+	this->x_extent      = 1;
+	this->y_extent      = 1;
+	this->z_extent      = 1;
 }
 
 void StopAllVehicles()
diff --git a/src/vehicle_base.h b/src/vehicle_base.h
index 7f524cb5ff..c2eb7f9e9f 100644
--- a/src/vehicle_base.h
+++ b/src/vehicle_base.h
@@ -223,9 +223,9 @@ public:
 	                         // 0xfd == custom sprite, 0xfe == custom second head sprite
 	                         // 0xff == reserved for another custom sprite
 	uint16 cur_image;        // sprite number for this vehicle
-	byte sprite_width;       // width of vehicle sprite
-	byte sprite_height;      // height of vehicle sprite
-	byte z_height;           // z-height of vehicle sprite
+	byte x_extent;           // x-extent of vehicle bounding box
+	byte y_extent;           // y-extent of vehicle bounding box
+	byte z_extent;           // z-extent of vehicle bounding box
 	int8 x_offs;             // x offset for vehicle sprite
 	int8 y_offs;             // y offset for vehicle sprite
 	EngineID engine_type;