Complex sentence: The XJ13 was a prototype racing car developed by Jaguar to challenge at Le Mans in the mid- 1960s, after it became apparent that the E-type could not be developed to be beat state of the art machinery from other manufacturers such as Ferarri.
Split into simpler sentences: The XJ13 was a prototype racing car developed by Jaguar in the mid- 1960s. It was an attempt to make a competitive racing car, after it became apparent that the E-type could not be developed to be beat state of the art machinery from other manufacturers such as Ferarri.