Feature: Display power-to-weight ratio in ground vehicle details GUI

src/train.h

@@ -228,6 +228,12 @@ protected: // These functions should not be called outside acceleration code.
 		return weight;
 	}
 
+	/**
+	 * Calculates the weight value that this vehicle will have when fully loaded with its current cargo.
+	 * @return Weight value in tonnes.
+	 */
+	uint16 GetMaxWeight() const override;
+
 	/**
 	 * Allows to know the tractive effort value that this vehicle will use.
 	 * @return Tractive effort value from the engine.