Canwest News Service: A group of Canadian automakers is pressing the federal government to tighten fuel regulations as a means of cutting down on the greenhouse gas emissions that cause climate change. The Association of International Automobile Manufacturers of Canada (AIAMC), which represents more than a dozen companies including Toyota, Honda and Porsche, says Canada has one of the weakest sets of regulations in the world when it comes to fuel quality and is among the weakest when it comes to enforcing …