No they will not catch fire when used properly. Anyone who says their vehicle caught fire either charged the battery for weeks straight and disregarded that they damaged the battery. Almost every one of our vehicles has the same type of battery that is in a normal car we drive which are SLA non-spillable batteries and when charged properly are extremely safe. The rest of the vehicle is plastic, metal and wiring... none of which are flammable unless you purposely put so much heat to it that you burn it. When you read review about a car catching fire what the customer means to say is that they had smoke coming from a motor that burned out. This can happen with the motors, but you will not see flames coming from the vehicle for a burned out motor.