Volkswagen of America (VWA) has said that its dealers will play a critical role in prodding the US government to develop regulations promoting diesel technology, according to The website said that VWA vice president-sales and marketing, Frank Maguire, said that his company intends to increase advertising of its diesel models, promoting the fuel economy benefits diesels produce over petrol engines, while not venturing into how much diesel engines have improved over the last 20 years.