Please search the rental car forums.

Dollar/Thrifty has "local" rates plus a flat per-rental drop charge. Cars are not "sent back," and this, like the higher daily rates from other companies, accounts for mileage depreciation and difference in demand. The reason for a separate drop charge per rental, rather than a higher rate per day, is as a discount brand, Dollar/Thrifty has a higher utilization, which means a smaller, less flexible fleet.

This option can be cheaper for short distance, long time one-ways. Still check all the companies, especially neighborhood store pickups.