The average car or truck has a number of flammable and highly dangerous fluids under the hood: gasoline or diesel fuel, engine oil, transmission fluid, power steering fluid, brake fluid and even engine coolant. All of those fluids are circulating when the car is on, and all of them can catch fire pretty easily if their lines, hoses or reservoirs take a hit. So even though one of the car's vital liquids is unlikely to start spewing or dripping out of nowhere -- generally, something else has to go wrong first -- the fact that all of these fluids are flammable to begin with is a problem in and of itself. Combined with another aggravating factor, like a car crash or a failed part, the result could be a fire. Though such a blaze is most likely to start in the engine bay, where all of these dangerous liquids are concentrated, keep in mind that some of them, like fuel and brake fluid, are moved along the entire length of the car.