Kevin Pearson, 37, turned over the ignition in Hylton Castle Road, Castletown, Sunderland, then fell asleep, a court heard.
Police were called to the scene after a report the vehicle was damaged on Saturday, April 16, and found Pearson, of Baltimore Court, Glebe, sleeping.
After being woken, he claimed he had been abandoned by a friend who had promised to take him home after a pub session.
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His admission to turning the engine on, saw him prosecuted for being in charge of a vehicle while unfit through drink, to which he pleaded guilty.
He avoided an instant driving ban for the offence, but magistrates in South Tyneside warned him he was walking a disqualification tightrope.
Prosecutor Claire Armstrong said: “Police were called after a report of damage to a vehicle which had its engine running.
“They found damage to a nearside wheel, and inside the car the defendant was asleep.
“He said that he had been driven home by another person and that he was drunk.
“While being booked in by the police, he made a significant statement.
“He said, ‘I did not drive the car but I did turn the engine on because I was cold.”
“He stated that he was in the back seat and had turned the engine on to keep warm.”
Before his arrest, Pearson gave a roadside breath test reading of 94mcg of alcohol in 100ml of breath. The legal limit is 35mcg.
The court also heard he was handed a driving ban in 2019 for failing to provide a sample for analysis.
Amy Rochester, defending, said Pearson had driven to a pub and had been unable to get a taxi home.
She insisted he had no intention of drink-driving and a friend who had volunteered to drive him home had instead abandoned him mid-way.
Magistrates handed him 10 penalty points and fined him £392, with £85 court costs and a £39 victim surcharge.
Harry Metcalfe, chair of the bench, said: “This is really your last chance, because anything after 10 points and you’re going to be banned.”