Original sentence: A large percentage of Auckland is still dominated by a very suburban style of building, giving the city a very low population density: although it has not much more than a seventh of the population of London, it sprawls over a considerably larger area, which makes public transport costlier than in high-density cities elsewhere
Edited sentence: A large percentage of Auckland is still dominated by a very suburban style of building, giving the city a very low population density: although it has not much more than a seventh of the population of London, it sprawls over a considerably larger area, a fact that reduces cost efficiency of public transport