A 19-year-old motorist who admitted driving his Honda 120 mph on an Iowa interstate told cops that he floored the vehicle last night “because a good song came on his stereo,” according to a court complaint.

After a witness called 911 to report a reckless driver was speeding and “swerving all over the road” a sheriff’s deputy spotted the suspect vehicle as it flew past him at 100 mph around 9:15 PM.

When the car was subsequently pulled over more than two miles up Interstate 380, driver Nicholas Bernard reportedly “admitted to going 120 mph at one point.” Bernard, seen at right, explained that he reached the top speed “because a good song came on” the stereo in his 2006 Honda Accord EX.

Bernard was only facing a speeding citation when he opened the glovebox to retrieve registration and insurance records. But then a deputy spotted a “large amount of marijuana” in plain view in the compartment. A subsequent search of the vehicle turned up a smoking pipe and other drug paraphernalia, cops report.

Bernard was charged with a pair of misdemeanor drug counts and booked into the Johnson County jail, from which he was released this morning.