Automobile engine fuel spray includes multi-scale free surfaces ; a liquid film forms at the outlet of the fuel injector, and then the liquid film breaks up into droplets. To simulate multi-scale free surfaces, we developed a hybrid particle/grid method where the free surfaces within a sub-grid region were simulated with the particle method, and other regions were simulated with the grid method. In the particle method, we used two particles for gas and liquid to simulate the interaction between them. We tested the new method on a dam-break problem, and the predicted configurations for the water column were consistent with measurements of Koshizuka and Oka. We then simulated the fuel spray near the outlet of an automobile engine fuel injector and found that our method correctly simulated the breakup of the liquid film.