He was meant to take a rental vehicle out for a distance of 50km but when John Clifton Tootell returned it, GPS tracking revealed the distance was more than 900km.
Tootell rented the "light vehicle" from Cross Country Rentals on March 26 with the agreement he could travel up to 50km, and anything above that would prompt a further fee he would be liable for, police prosecutor Sergeant Drew Morrison said.
If he did not use the full amount of kilometres, he would be refunded for that amount.
On March 28, the 31-year-old took the vehicle back, claiming it had gone only 12km. The odometer appeared to back up his claim. But it was later discovered there were marks on the vehicle suggesting the odometer had been removed, Mr Morrison said.
The company then used GPS tracking to see how far the vehicle had actually gone, and found it had travelled 930km. Tootell did not pay the extra $484.
He appeared in the Whanganui District Court on Tuesday, where he pleaded guilty to theft.
Defence lawyer Stephanie Burlace said Tootell had offered to pay the extra money off but could not pay it all at once. He was on a job-seeker's benefit, soon to become an invalid's benefit, she said.
"The light vehicle was used by his sister-in-law," Ms Burlace said. The woman's daughter had used the vehicle and that was where "things have gone awry".
Judge Allan Roberts discussed reparation with Ms Burlace.
"Perhaps the daughter might like to chip in," he said. "A person like that taking a car and clocking up miles, of course we can't expect them to pay."
He convicted Tootell and ordered him to repay the money at a rate of $10 per week.