Richardson, who was also found guilty of a separate dangerous driving charge on 21 April, had numerous previous motoring offences, the court heard.
Prosecution counsel Phil Barnes KC told the court Richardson had previous convictions for 28 offences with a “significant history” of driving-related crimes.
This included careless driving and failure to stop or report an accident in 2011, driving with excess alcohol and driving whilst disqualified in 2012 and driving whilst disqualified and uninsured in 2013, the court heard.
In 2023, he was convicted of driving without a licence and insurance.
In mitigation, defence barrister Jaime Hamilton KC said the absence of premeditation was a “significant feature” in the case, and that Richardson had not intended to use his vehicle as a weapon.
He said: “This defendant did accept that his actions did lead to the death of Mr Mullins and through me, he expresses his remorse.”
The judge said Richardson would face a whole-life disqualification from driving as he was a driver with an “appalling” record.
She said: “You took away a life and in doing so you caused devastation to a family and a community.
“I find that you would be a danger to other road users indefinitely.”
She added: “You deliberately used your car as a weapon over a prolonged period.
“You have repeated convictions for a range of serious driving offences over a 15-year period.
“This demonstrates the complete contempt you have for the law.”
The judge also said Richardson drove dangerously the day after the murder, at a time when “you knew you had seriously injured or killed a man with your driving”.