The car you will be driving has a powerful water spurt that can be used to literally wash all the junk from the streets. You just need to ride around the city, find the most contamination areas and turn on your equipment. You will see how all the litter flows away under the pressure of water and the streets become clean and shiny again. The citizens will definitely appreciate such a contribution to their welfare and your reputation will grow. The city council will start entrusting you with more and more important and complicated missions. And you will get rewarded for them accordingly.
How can you spend the money earned in the process? You will be able to upgrade your transport and make it even more efficient in removing dirt and trash. There are various improvements you can buy and they will allow you to work even faster and with better results. Gradually, you will clean the entire city and everyone will be surprised to live in such a clean and ecologically healthy environment. Good luck!