As a consequence of the undesirable performance experienced with the early Romanian-built members of the class, the locomitives subsequently built feature significant modifications to help prevent this experience being repeated. This attention to improving its operational performance is likely to be amongst the reasons why the Class 56 would prove to be operationally superior in most metrics to the subsequent Class 58, which in turn has led to the type having a longer lifespan in comparison to this newer locomotive. It had been largely due to the initially negative experiences with the Class 56, which had caused dissatisfaction amongst several of British Rail's freight customers, that BR officials had initiated work on the Class 58, although it differed substantially due to a new focus for the latter upon the highly competitive international market.