An interesting discussion point @Informedatlast.
There are several now closed topics discussing laundry detergents, as well as the Choice guide linked in the latest review.
Worth a read: Laundry detergent testing - cold water
My recollection is Choice tests all detergents in cold water. On using less the suggestion some past advice was to experiment at home to find the best results for the least detergent. Water quality, what we wash and the model of washer can influence the outcome.
EG We only have roof, rain water stored in an unlined concrete tank. Everyday washing works fine in our small size top loader with a half scoop of an eco friendly powder. For the outdoor work in the yard clothing covered in grime etc the same product needs near to a full scoop, and warm water, with sometimes a hot wash. You can never tell what bacteria, mites etc come back with you from the bush.
