Toyota does not recommend towing with the Prius, so the factory does not provide any engineering data or specifications for towing. That said, there are some light-duty hitches available through the aftermarket that will install on a Prius. They typically are not load-rated, as they were designed to carry add-on fixtures like a bicycle carrier. However, it may be possible to add a draw bar in the appropriate size that can accept a trailer ball. If you can obtain the correct wiring converter for trailer lights, then what's to stop you? If you've decided to pursue things this far, a good rule of thumb would be to not exceed the manufacturer's Gross Vehicle Weight rating, which is the combined weight of the car, fluids, passengers, luggage (and trailer). Don't even mention warranty coverage...it's not gonna happen.
Toyota does not recommend towing with the Prius.
The maximum cargo capacity of the 2013 Toyota Prius is 39.6 cu.ft..
The maximum cargo capacity of the 2001 Toyota Prius is 11.8 cu.ft..
The maximum cargo capacity of the 2010 Toyota Prius is 39.6 cu.ft..
The maximum cargo capacity of the 2014 Toyota Prius is 39.6 cu.ft..
The maximum cargo capacity of the 2011 Toyota Prius is 39.6 cu.ft..
The maximum cargo capacity of the 2012 Toyota Prius is 39.6 cu.ft..
The maximum cargo capacity of the 2012 Toyota Prius-V is 67.3 cu.ft..
The maximum cargo capacity of the 2014 Toyota Prius-V is 67.3 cu.ft..
The maximum cargo capacity of the 2013 Toyota Prius-V is 67.3 cu.ft..
5000 lb towing capacity
* Towing capacity: 907kg (2,000lbs)