A 30-year-old man, Nagendra, died after detonating an explosive inside a car on National Highway-4.
The incident occurred in Sira taluk, Tumakuru, during a journey from Bengaluru to Ankola.
The victim allegedly assaulted his girlfriend, Ramya, before triggering the explosion.
Local police, led by SP Ashok K.V., have registered a case and are investigating the event.