Car Hire in Paraguay
Car hire and rentals conditions in Paraguay explained

General
The AA recommend an international driving permit but it is possible to arrange car hire without one if you are travelling as a tourist. You will need your UK driving licence (preferably with a photocard).
Driving in Paraguay is not for the nervous driver as the roads are often of poor quality and drivers routinely ignore traffic regulations and drive without insurance. It is important to make sure you are adequately insured.
Limited mileage contracts are quite common in Paraguay and quite restrictive at a typical 100km per day allowance. Unlimited mileage contracts are available from some suppliers.
Car Hire Insurance
Most car hire will be inclusive of collision damage and loss waivers, excesses do vary quite a lot and can be over US $1,500 making car hire excess insurance very worthwhile.
Don't assume European levels of third party insurance will come with your rental especially if you hire from one of the American chains. If you consider the amount of cover provided to be inadequate, you can purchase Supplementary Liability Insurance (SLI) with your car hire excess insurance. Be aware though, that some policies only offer SLI in the USA and Canada.