• Lyons was returning from a night out in Manchester and had been drinking beer and wine and taking valium
Paul Lyons admitted consuming a cocktail of alcohol and drugs before ramming father-of-two Mark Fleeman off the M74 in Lanarkshire.
Mr Fleeman, 32, from Uttoxeter, Staffordshire, died when his van was sent careering across the motorway near Larkhall.
Lyons, a well-known figure in the Glasgow underworld, fled to Spain to escape justice but was extradited back to Scotland after he was arrested at an airport in Alicante.
The 28-year-old was at the airport in Spain to meet his young son when police pounced.
He pleaded guilty to culpable homicide and attempting to defeat the ends of justice at the High Court in Glasgow last month.
Today he was jailed at the same court for 12 years, with an additional three-year supervision period, and banned from driving for life.
Lord Woolman said: "As a result of your appalling conduct that night, one man is dead, another man was severely injured and has been left permanently disfigured.
"There were two important reasons why you should not have been on that road that night.
"First, you were disqualified from driving. Secondly, you were unfit to drive because you were under the influence of drink and drugs."
He added: "It is clear that you were prepared to drive with complete recklessness."
Shopfitter Mr Fleeman was driving to work along the M74 in the early hours of June 4 last year when Lyons repeatedly tried to crash his own van into him at more than 70mph.
The vehicles eventually collided, with Mr Fleeman's overturning several times before landing at the side of the carriageway.
His passenger, 17-year-old student Lee Allsup, also from Uttoxeter, was seriously injured in the crash.
Lyons, who was driving home from a night out with friends in Manchester, had been drinking beer and wine and took valium pills during the trip north.
Advocate depute Iain McSporran told the court last month that Mr Fleeman had initially gestured at Lyons because of his erratic driving.
He said: "It appears that the accused's response to this gesture is what led to Mr Fleeman's death."
The court heard that Lyons said to one of his passengers: "I'm going to sideswipe him."
He sped away from the scene after the van lost control.
Mr Fleeman and Mr Allsup were thrown from the vehicle as it rolled.
At just after 4.30am on June 4, a 999 call was made from Mr Fleeman's mobile but the operator could only hear the sound of a crash, the court heard.
Lyons was originally charged with murder or an alternative charge of causing death by reckless driving.
He was also accused of attempted murder or an alternative charge of reckless driving, assault to severe injury, attempting to defeat ends of justice and various charges under the Road Traffic Act 1988.