Hi there,
The reason for this it is that at the moment no
Car Rental Companies carries the special insurance that allows you to leave
Costa Rica to
Panama or
Nicaragua in the same car.
Your best bet would be to rent with Poas
Rental Car in Costa Rica. They have an office in Puerto Viejo and then cross to the border to go to Bocas del Toro in Panama, then take a car from dollar to drive into Panama.
Please check out these links for more sugesstions on what to do in Costa Rica and Panama
http://www.destination360.com/centra...ary-costa-rica and
http://www.destination360.com/centra...e-travel-tours
Hope this helps
VacationBuddy