The 53-year-old man was discovered on the A82 between Crianlarich and Tyndrum in Stirlingshire at around 8.25am.
He was airlifted to hospital in Glasgow and later died.
The injured man's car was discovered nearby and the road was briefly closed.
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Hide AdCentral Scotland Police said they were not treating the incident as suspicious.
The man was from the Lanarkshire area.