No maximum mileage criteria, only age. A lot of Uber/Lyft drivers will buy or rent a relatively new car with higher than average mileage. Rental companies are finding this a lucrative way to dispose of busted up 2 year old sedans with 50k mi.

In some suburban areas, cars up to 15 years old are allowed. Buying a $3k car with over 100k mi is often the most profitable choice, especially when drivers increasingly make hardly anything per ride.