An automobile fuel pretreatment device includes an instantaneous constant-temperature heating device including a fuel tube which allows fuel to flow, a heating unit positioned on and heating an outside surface of the fuel tube, and two spring clamp boards enclosing and clamping the heating unit on the fuel tube. Each of the spring clamp boards has a locking hole formed adjacent to a first free end and a locking tab formed adjacent to a second free end. The locking tab of each of the spring clamp boards is received through the locking hole of the other one of the spring clamp boards to engage the first free end of the other one of the spring clamp boards. A magnetization combustion-enhancing device includes two permanent magnets located adjacent to the fuel tube to induce magnetization on the fuel flowing through the fuel tube.