I use my same personal vehicle to conduct work for two different rideshare companies. Would I input property tax expenses on my vehicle for both rideshare companies?

No, you cannot claim your vehicle property taxes for each ridesharing company as this would be double-claiming. In fact, you can report your ridesharing business on one unique Schedule C for both companies as they are in the same line of work.

You should apportion vehicle expenses proportionately between your business use and your personal use, and only claim the business use portion.