No doubt it's a Fiat 1500 from 1940 (as per the license number reflects) The first Pegaso cars are from 1951 and the Pegaso Spyder Serra from 1956. In front of the dificulties of buy a modern car until the 60's in Spain some people use to rebody their existin cars into a more modern look, in this case that body was made by Serra in 1953 as explain the book of Serra's history.