[lendaddy]

"You're not actually allowed to open the hood at a routine traffic stop. The officer is allowed to search areas accessible to the driver for weapons as a safety measure. However, the trunk, which is not accessible to the driver, cannot be searched without probably cause. The engine bay, similarly, is not accessible to the driver while operating the vehicle, so searching it is not legal."

Actually you can search anything the driver gives you permission to search.