Once upon a time, there was a curious young boy named Alex. He loved to explore and learn about how things work. One day, he became interested in knowing how car engines work. So, he decided to visit Karl Benz, the famous inventor.

When Alex arrived at Karl Benz's workshop, he saw many amazing machines and tools. He felt very excited to meet the inventor. Karl Benz smiled and asked, 'Do you want to know how a car engine works, Alex?'

Alex nodded eagerly and replied, 'Yes, Mr. Benz! I really want to understand.' Karl Benz picked up a small toy car and showed it to Alex. He explained, 'A car engine works like the heart of a car. It gives power to make the car move, just like your heart pumps blood to make your body move.'

Alex looked at the toy car's engine and asked, 'But how does the engine give power, Mr. Benz?' Karl Benz smiled and said, 'Great question, Alex! Inside the engine, there are tiny explosions called combustions. These explosions create a force that makes the car's wheels turn.'

Karl Benz continued, 'To make these explosions happen, we need fuel, just like food for our bodies. The fuel is mixed with air, and when a spark ignites the mixture, the explosions occur. This is why we need fuel in our cars to make them run.'

Alex was really starting to understand now. He asked, 'What happens when the car runs out of fuel?' Karl Benz replied, 'The car stops because there is no more fuel to create the explosions. Just like we need to eat to have energy, cars need fuel to keep running.'

Alex was amazed by how the car engine worked. He thanked Karl Benz for explaining everything so well. Alex left the workshop with a big smile on his face, feeling even more curious about the world of inventions.