The article mentions that the energy input from combustion is significantly higher than that from insolation in Manhattan in January, but also that the primary

The article mentions that the energy input from combustion is significantly higher than that from insolation in Manhattan in January, but also that the primary driver of the heat island effect is from building materials. Obviously asphalt roads and (especially) parking lots are an indirect contributor to low-albedo and low-permeability landscape. Taken together, how much of the heat island effect is due to the automobile? Would a pedestrian + transit city, with aggressive tree canopy, still be a heat island?