Absolutely not. If law enforcement asks for permission to search you or your vehicle you have the legal right to decline. Demand a warrant, make law enforcement present their case to a neutral judge before giving up your constitutional right. There are circumstances under which law enforcement can search even without your consent. Do not resist or this could lead to additional charges, not to mention violence from the officer. If officers fear for their safety they can pat down your clothing. This is a search for weapons. In order for officers to search your vehicle without consent they must have probable cause to believe there is evidence of a crime in your vehicle, they are searching for weapons in the vicinity you are sitting, or after you have been arrested.