Here are some specific things that would happen:
* The engine would not be able to start. The engine needs fuel to combust and create power. Without fuel, there would be no combustion, and the engine would not be able to turn over.
* If the engine is already running, it would eventually stall. As the fuel in the engine is used up, the engine would begin to run lean. This means that there would be too much air and not enough fuel in the combustion chamber. This would cause the engine to lose power and eventually stall.
* You would not be able to drive your vehicle. Without fuel, your vehicle would not be able to move. You would be stranded wherever you were when the fuel ran out.
It is important to make sure that you have enough fuel in your vehicle before you start driving. If you run out of fuel, it can be a very frustrating and inconvenient experience.
