Jacqueline Dewhurst, 45, was double the limit for both alcohol and cannabis when she lost control of the Vauxhall Meriva which she had bought on eBay just a week earlier for £550.
Paramedics found the vehicle upside down in a field near Wragby after Dewhurst drove her daughter's partner, Nathan Williams, from Sheffield to Skegness despite drinking and taking cannabis at a party earlier that night.
Mr Williams, 31, a rear seat passenger, was thrown from the car and suffered a serious spinal injury which left him paralysed from the waist down and reliant on a wheelchair.
Police bodycam footage which was played in court showed Dewhurst refusing to give either a roadside breath or drugs test following the 5am crash on August bank holiday last year.
Lincoln Crown Court heard Dewhurst was clearly "intoxicated and uncoordinated" at the scene and claimed the driver of the crashed car had run off.
Dewhurst had taken vehicle to a garage in Sheffield the day before the crash after noticing a problem with the heavy steering but did not return when the mechanic said he could not look at it straight away, the court was told.
The steering problem reoccurred around 30 minutes before the crash but Dewhurst continued the journey to Skegness with her partner in the front passenger seat and Mr Williams in the rear.
When the steering problem happened a third time Dewhurst careered off the A158 at Langton by Wragby.
Phil Howes, prosecuting, said a vehicle examiner later found an intermittent problem with the power steering of the Vauxhall Meriva which would have been obvious to the driver because of the heavy feel and a warning light coming on.
When Dewhurst finally consented to blood tests at hospital six hours after the crash back calculations showed she was double the legal limit for both alcohol and cannabis.
During police interview Dewhurst accepted she had noticed the problem with the steering and had continued to drive the vehicle after turning off the ignition which cleared the warning light.
Questioned by officers, Dewhurst accepted the steering was dangerous, and said she had been blocked by the seller of the car after being sold a "dud."
Dewhurst, who had a previous conviction for drink driving in 2017, also admitted drinking four cans of larger on the Sunday afternoon before the crash and then attending a party in Sheffield where she drank more alcohol and took cannabis.
Despite her condition Dewhurst agreed to a request from Mr Williams to drive him to Skegness during the early hours of the morning.
The court heard that despite his catastrophic injuries Mr Williams had not cooperated with the police investigation and did not want his mother-in-law to be jailed.
In a victim impact statement, which was read out in court by the prosecutor, Mr Williams said he had known Dewhurst since childhood - but the crash had left him completely reliant on a wheelchair and suffering from nightmares.
Gordon Stables, mitigating, said Dewhurst had made a number of poor choices starting with the buying of the car, but was a vital carer for all her family.
Passing sentence Judge John Pini QC said while it was clear Dewhurst's family did not want her jailed the offence was aggravated by her lack of sleep, the consumption of drink and drugs and her knowledge of the steering fault.
"Mr Williams victim impact statement makes clear his life has been totally destroyed," Judge Pini said.
Dewhurst, of Nodder Road, Sheffield, admitted causing serious injury by dangerous driving on 30 August last year.
She was also banned from driving for five years and must take an extended retest.