THE heating, ventilation and air-conditioning (HVAC) system is unchanged from the VT Commodore, which improved airflow by 15 per cent over VS. Larger diameter rear ducts improved airflow to rear seat occupants by 30 per cent over VS. A large fascia, buttons and display make for good ergonomics and visibility. Air-conditioning is optional on Executive, with a climate-control system standard on Berlina and Calais grades. A large capacity, variable stroke air-conditioning compressor was employed to remove temperature fluctuation.