Tide HE
When my Persil supply runs low, I use Tide HE (HE = High Efficiency, mainly front load machines plus a few top load machines like Calypso that use small amounts of water compared to a traditional top loader). In general, you use regular old fashioned Tide in normal top loaders, and Tide HE in front loaders.
Tide doesn't clean or rinse out as well as Persil, but it's one of the best that can be easily purchased here (yes, you can buy Persil here at stores that sell Miele appliances, if you don't mind paying $50 for a box that contains enough Persil for 50 washes....).
Sears Ultra Plus HE detergent is believed by many on this board to wash as well as Tide HE (or better) at lower cost, but to buy it, one must travel to a Sears store. Tide HE can be purchased at nearly any supermarket or discount store (Target, WalMart, etc.). Ultra Plus is not to my knowledge sold outside of Sears stores.
Americans have been using Tide since 1946. Like Germans believe in Persil.
Here is a brief history:
"Tide
In the 1920s, Americans used soap flakes to clean their laundry. The flakes performed poorly in hard water, leaving a ring in the washing machine, dulling colors, and turning whites gray. Procter & Gamble began an ambitious mission to change the way Americans washed their clothes. Researchers discovered two-part molecules which they called synthetic surfactants. Each part of the "miracle molecules" executed a specific function--one pulled grease and dirt from the clothes, while the other suspended dirt until it could be rinsed away. In 1933, this discovery was introduced in a detergent called "Dreft," but it could only handle lightly soiled jobs. The next goal was to create a detergent that could clean heavily soiled clothes. That detergent was Tide®.
Created in 1943, Tide detergent was the combination of synthetic surfactants and "builders." The builders helped the synthetic surfactants penetrate the clothes more deeply to attack greasy, difficult stains. Tide was introduced to test markets in October 1946 as the world’s first heavy-duty detergent. Consumer response was immediate and intense. Tide detergent outsold every other brand within weeks. It became so popular that store owners were forced to limit the quantity purchased per customer.
Tide detergent was improved 22 times during its first 21 years on the market, and Procter & Gable still strives for perfection. Each year, researchers duplicate the mineral content of water from all parts of the United States and wash 50,000 loads of laundry to test Tide detergent’s consistency and performance."