We are going to Poland for a month in September and would like to rent a car from a local Polish agency in Warsaw. We rented a car from a local agency last September in Bucharest, Romania and it was great! It also saved us $500 from the cheapest rate we could get from US and big international companies. We would appreciate any recommendations.
When I want to rent from a local agency I always google search for "Warsaw Auto Rental Agency".
There may be other ways to find local rental agencies. I found Rentawreck in Stockholm (using that search method) to be a licensee with a fee about half the international agency fees.
And my diesel car was only two years old and ran perfectly. His primary business was a repair garage! I took that to be a good recommendation.