The crash happened at around 7.45am today when the car, a Toyota C-HR, travelling southbound on the M6, exited the motorway at the Charnock Richard Services and struck a metal fence.
North West Ambulance Service attended, but the driver - a woman in her 50s - was sadly pronounced dead at the scene.
Sgt Phil Baxendale, of Lancashire Police Tactical Operations, said: “This was a tragic incident where a woman has lost her life and my thoughts are with her family and friends at this time.
"I would appeal to anyone who saw this vehicle, or who has dashcam footage of it, either on the motorway before the collision or the collision itself, to get in touch."
Anyone with information should contact police on 101 quoting log 0236 of Sept 22.