Your car is filled with a variety of fluids that keep it running. If you notice a puddle under your car, do not panic. You can quickly identify what the mysterious fluid is and get it fixed accordingly. If the fluid is green in color, then you are dealing with a coolant leakage; if the fluid smells like gas, then your gas tank needs a replacement; if it is a yellowish-brown puddle, then it is probably engine oil. In this case, you need to get your engine checked immediately.