continuing on Launderess' comments about water temp
I wonder how much of the miracle was due to the shirts' first hot wash in a front loader, vs. the fact that it was a Miele, vs. the fact that HE detergent was used.
I have a modest Frigidaire 2140. I remember, the first week I owned it, doing a load of white underwear and white shop towels (hand towel sized, I have a stack of them from Costco for cleaning jobs) on hot/heavy soil cycle (with heavy soil and extra rinse options selected). The machine does not have an integrated heater, but it sits right next to the water heater which is set to about 140 F (60 C). When the wash was done, I was astonished at how white everything was. It looked as if I'd used bleach, when in fact I used only All HE liquid, no bleach, and no other additives. I realized then that these articles were very yellowed from the old top loader, and that they needed only one wash in the new machine---however "entry level" that washer may be---and suddenly they were as white as if bleach had been used.
Normally, I wash my dress shirts and khaki trousers (my work clothing)---all of which are 100% cotton from LL Bean, with the no-wrinkle finish---on Perm Press cycle, which spins at a lower speed to avoid setting wrinkles. I normally use Warm temperature. What I have noticed is that perspiration/deodorant stains eventually appear on white or light blue shirts, and that I can eliminate these by washing in hot water with heavy soil (longer agitation) option on the Perm Press.
I wonder if the Perm Press cycle is really only needed for more delicate blends and synthetics, as everything I am washing that is "perm press" is really all-cotton and probably can tolerate a more vigorous "Normal" cycle. I probably should experiment by using "Normal" cycle to check if wrinkles are an issue after drying---the clothes would be drier if I used Normal, and I could de-select "extra spin" time.
My washer doesn't gradually heat the water from cold to 60 C as Launderess described for Mieles, but even my humble Frigidaire got amazing results when I switched from a POS GE TL to a Frigidaire BOL FL 2140 in 2006. I know someday the spider will break, but I am happy to report six years of trouble-free operation, no service calls at all.