Residents living near the Ratcliffe Crescent underpass in Florey were woken early on Sunday after a car was set alight directly beneath the bridge.
ACT Policing confirmed the vehicle, a green Mazda convertible, had been stolen, with its number plates removed prior to the incident.
Emergency services were called to the underpass, near the Florey shops in Belconnen, around 2am on September 13 following reports of fire and heavy smoke. Firefighters reached the spot and extinguished the blaze, but the severity of the fire left the vehicle completely charred. Its skeletal frame remained under the bridge on Wednesday evening.
It is believed the car was intentionally driven onto a pedestrian-only footpath under the bridge before being set ablaze.
"At this stage, the investigation is ongoing," an ACT Policing spokesperson said.
Police are yet to determine where the vehicle was stolen from or the identity of the person(s) who drove it to the scene. The footpath was temporarily cordoned off to the public for safety and forensic examination.
Anyone who noticed suspicious activity near the Florey shops prior to 2am on Sunday is urged to contact Crime Stoppers on 1800 333 000 or via crimestoppers.com.au, quoting reference number 8497677.