Enter TRUE in the advanced setting called DISABLEMINQTY. By default we use the per car qty as the unit of measure to add to the cart. If you prefer to allow a customer to order 1 brake disc instead of 2 then disable this setting. This is not to be confused with a pack qty. If an item has a pack qty the system will always respect it. Another words if brake discs are sold in packs of 2, you have to order in increments of 2. The system assumes that 'each' is the default unit of measure but will respect packs if the data is provided by the supplier or the catalog system in use.