Chloe Leh Matthews, 21, from Higgins, was arrested on Friday after the alleged early morning actions which destroyed the garage of a Kambah home and the Subaru WRX inside it.

The ACT Magistrates' Court heard the woman had earlier threatened to steal the car if the relationship ended.

Court documents read to the court on Saturday said the woman left a bar about 1.30am on September 2 and, with the help of friends, got into the garage.

"I got bottle of metho and some newspaper and vwoom," she later allegedly texted a friend.

"I'm a badass now."

In another alleged text to a friend she said the fire turned her on.

The prosecutor said the end of the short relationship was the motivation for the conduct.

ACT Policing said the fire spread to the main part of the Kambah residence and caused substantial roof damage, with an estimated damages bill of $122,600 to the residence and property.

"The four occupants who were inside the house were alerted by a neighbour and managed to escape the blaze," police said in a statement.

"A 55-year-old man suffered burns to the soles of his feet and was treated at the scene by ACT Ambulance Service."

Magistrate Bernadette Boss granted the defendant bail on conditions including her reporting to police three times a week, and not contacting the former boyfriend and a list of other people.

No pleas were entered.

The matter returns to court on December 8.