In United States v. Smith, 30 F.3d 568 (4th Cir.), cert. denied, 513 U.S. 1028 (1994), the police were keeping a suspect under surveillance for suspected cocaine distribution.
When they saw him walking toward his car, carrying a bag, they stopped him and asked whether they could search the bag. He said yes, and they searched it and found nothing.
The police then asked the suspect whether they could search his car. He made no verbal response, but approached the car and unlocked it. The police searched the car and found cocaine.
Upholding the lower court's denial of a motion to suppress the cocaine from evidence, the Fourth Circuit held that the suspect's act of unlocking his car door in response to the request by police to search it constituted an implied consent to search. Smith, 30 F.3d at 571.