Police have released CCTV pictures of a man they believe may have information about the theft of fuel at Rothwell Service Station, on the A14 eastbound, near Rothwell.
The passenger of a silver Audi A3 dispensed fuel into the vehicle, got back in without making any attempt to pay, and the driver drove off.
The incident happened on Sunday, April 1, at about 6.30pm.
The man pictured, or anyone who recognises him, is asked to contact Northamptonshire Police on 101 or Crimestoppers on 0800 555111. The incident number is 18000147649