Firefighters were called in to battle the fast-moving fire that started in the garage of a house in affluent Prueksa Pirom housing state in Soi Ratchapruek 16 early in the afternoon. It took them 30 minutes to bring the blaze under control.
Destroyed were a Porsche, a BMW, a Mini Cooper and a Hyundai van.
Witnesses said no one was at home when the fire erupted and a security guard who was patrolling the area alerted authorities.
House owner Passarika Jirapongtrakoon said all family members were at work at the time of the fire.
When told of the incident by a neighbour, she said she panicked and rushed home. Several explosions were heard during the fire, but she said none of the cars were fuelled by liquefied petroleum gas.
The flames did not damage the house as the garage was located far from it, police said.