Utilize the input text as a context reference, choose the right relationship between PACCAR and truck from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Dan Kieffer of PACCAR Inc., speaking for a group of heavy-duty North American truck manufacturers including Volvo and Daimler, said, “Unnecessarily stringent engine standards will only exacerbate today’s trend of delaying new truck purchases,” and consequently keep older, not-as-clean trucks on the road.

Answer: product_or_material_produced