The 36-year-old was assisted by officers off the A1 in Edinburgh before being involved in the fatal crash at the Harthill Services on the M8, which is about 30 miles away, the Police Investigations and Review Commissioner (Pirc) reported.
It said police had spotted the man’s car parked dangerously on an unlit section of the dual carriageway without lights shortly after midnight on 29 March.
The Pirc said officers carried out checks to see if the man was fit to drive, including a breath test, which was negative.
He was escorted to a “safe area in a car park” and given advice on safe driving.
The Pirc said he told police he was tired and would rest in his car before driving to a relative’s house in Fife.
He was moving from his home in England and had taken tablets for a headache, washed down with alcohol.
The officers did not consider the man was further impaired by drugs, and they left him.
However, at 2:20am the man crashed into a stationary articulated lorry and died at the Harthill Services.
CCTV showed the car did not slow down as it left the motorway for the service station before hitting a kerb and colliding with the lorry.
Police Scotland referred the incident to the Pirc, which concluded the officers’ actions were “appropriate and in accordance with police procedures”.
The Pirc said it was not known why the man had not slowed down or taken avoiding action to avoid a collision.
Police Scotland had appealed for information and dashcam footage about the crash the day after the black Renault Laguna hit the lorry.
Sergeant John Tait, of its road policing unit in Motherwell, said at the time: “The car entered the slip road, mounted a grass verge and crashed into the lorry which was stationary at the time, parked in the HGV lorry park.”