The paper presents an overview of the latest available information about heat release rate (HRR) and gas temperature development in tunnels. Results from major fire test series in tunnels are presented, as well as fire tests with vehicles in other type of applications. The HRR and temperature development from the large-scale fire tests performed in the Runehamar tunnel in 2003 is presented. These tests included four tests with different HGV trailer fire loads. Heat release rate over 200 MW and gas temperatures over 1300 oC were measured.