Receiving payments from multiple clients doesn't necessarily split your work into multiple businesses. You are the business operator, and it's perfectly reasonable that you provide essentially the same service to multiple rideshare companies all under one umbrella.
It's probably simplest and most sensible to include all rideshare income on a single Schedule C and then only calculate the vehicle expenses once.
No, you will add the car just once. You will enter the total miles driven for 2022. Next enter the total business miles driven for all the clients from 01/01/2022 to June 30/2022. Then the total business miles driven for all the clients from 07/01/2022 to 12/21/2022.
Here's the steps.
7. On the screen below, answer the questions > Continue.
8. On the screen below enter the total miles driven > Miles driven between 01/01/2022 and 06/30/2022 > Miles driven between 07/01/2022 and 12/21/2022.
9. Complete this section.