Complex sentence: The XPT was a success, with high patronage requiring 12 additional trailer cars to make up six sets of seven passenger cars, enabling the extension of the "Mid-North Coast XPT" from Kempsey to Grafton, becoming the "Holiday Coast XPT" from 1985.
Split into simpler sentences: The XPT was a success, with high patronage forcing the order and delivery of an additional 12 trailer cars to allow six sets of seven passenger cars. This allowed the extension of the "Mid-North Coast XPT" from Kempsey to Grafton, becoming the "Holiday Coast XPT" from 1985.