Fires in buses are a common and global problem. About 2/3 of all bus fires start in the engine compartment of the bus. This has naturally led to efforts of reducing the fire risk of bus engine compartments. A common way to limit the extent and consequences of bus fires is to install automatic fire suppression systems in the engine compartment of the buses. SP Fire Research has developed a method to test and evaluate such systems under standardized and realistic conditions. An amendment of UNECE Regulation 107 has made fire suppression systems to become mandatory on buses in many European countries with test requirements mainly based on SP Method 4912. The amendment will likely improve the fire safety of buses in Europe substantially. Standards for fire suppression systems are also progressing in other countries and regions.