SUNAT (Peru authority of Aduanas) made free and generaly accessible vehicle status information system.
I tested it on car plates here in the parking in Cusco and works perfectly for Peruvian cars. The cars with transit only registration (90 days stay) as is the case of my van are NOT listed.
Hope this could help someone willing to buy a Peruvian car.
¨Here comes the link: http://www.sunarp.gob.pe:8080/cel2/verificaPlaca2.aspx