Arsonists set fire to a car near Old Hurst on Tuesday night.
Firefighters from Huntingdon were called to a stretch of the A141 between between Old Hurst and neighbouring Woodhurst at about 10.20pm.
A spokesman for Cambridgeshire Fire and Rescue Service said: “Firefighters arrived to find a blue Volkswagon Passat on fire. Wearing breathing apparatus they extinguished the fire using a hose reel and returned to their station by 11.15pm.”
An investigation revealed that the cause of the fire was deliberate.
Anyone with information should contact police on 101 or Crimestoppers, anonymously, on 0800 555111.