When Dylan Grant Woodley heard of his mate's feud with an ex-girlfriend he decided to make her car "go boom".

But the arson was misguided — it was not her car. The man had seen his ex-partner driving the Toyota station wagon but it actually belonged to her mother.

Woodley, 25, and his co-accused — who has pleaded not guilty to arson — were together on the evening of July 14.

The second man explained his "grievances and animosity" with the woman he had formerly been seeing.

Woodley suggested they blow up her car.

"Make it go boom," he said.

So the pair drove to a South Dunedin petrol station and purchased fuel.

Carrying an empty ice-cream container, the petrol can, a rag and a lighter, Woodley approached the Toyota, which was parked on a residential street, the Dunedin District Court heard.

He soaked the rag in fuel, filled up the container, placed it under the engine, set the rag alight and fled back to his friend's waiting vehicle. But Woodley's plan was thwarted by a member of the public who spotted him leaving the scene.

They called the fire service, while a "good Samaritan" passing by used a fire extinguisher from his vehicle to douse the flames.

Despite the quick response, the front grille of the car was melted and the bumper and radiator were also damaged.

Woodley's bungled endeavours did not end with the arson.

When he was interviewed by Probation before sentencing this week, he told them he would not do community work or counselling and would only undertake an electronically monitored sentence if it was community detention.

Even then, the defendant said he would only abide by a weekday curfew because he had "other plans" for the weekends.

Judge Kevin Phillips said it showed a "total lack of remorse". But defence counsel Ann Leonard said her client did not mean to come across as arrogant.

She told the court he suffered from ADHD but had not been medicated.

"He is mystified and horrified at his offending. He says he really cannot explain why he did this thing," Leonard said.

"Once he did it he said he sat back and thought about it and couldn't believe he'd done such a stupid thing."

Judge Phillips said the location of the crime was an aggravating factor.

"It is quite clear this car was parked in a residential area," he said.

"You were quite prepared to blow up a car in such an area without any thought of consequences."

Woodley was jailed for a year and ordered to pay the victim $713 once he was released.

The co-defendant will be back in court next month.