Four full-scale fire experiments using 4-door sedan passenger cars were carried out. The cars were ignited either at the splashguard of the right rear wheel or at the left front seat in the passenger compartment with a gasoline spill. The temperature inside the burning car and the mass loss rate were measured. The burning of the 4-door sedan was composed of three compartmental fires: the engine compartment, the passenger compartment, and the rear part inclusive of the fuel. In the experiments where ignition was initiated at the splashguard, the flame spread in the following order: to the rear part of the car, to the passenger compartment, and to the engine compartment. Breakage of the window glass markedly affected the spread of fire into the passenger compartment. The quantity of gasoline in the fuel tank also affected the speed of spread of the fire, because the gasoline ignited at an early stage of the fire. In the experiment where ignition was initiated in the passenger compartment, the fire gained force after the windshield was broken entirely. The flame spread in the following order: to the passenger compartment, to the engine compartment, and to the rear part of the car. The temperature within the passenger compartment peaked at 1000 °C. The heat release rate (HRR) curves showed several peaks depending on the burning of the three compartments. The HRR increased markedly when the fire spread to several different parts of the car at the same time. The HHR peaked at 3 MW when the passenger compartment and fuel (gasoline) burned simultaneously. The measured HRR curves were characterized by superposition of a Boltzmann curve and a Gaussian curve in order to obtain a model, which allowed us to make a more precise prediction of the fire spread probability from a burning car to nearby structures. The HRRs of burning cars were described by the sum of HRR from each compartment. © 2008 Elsevier Ltd. All rights reserved.