Electrolux calls it "smart load sensing," They tout it on the web page for their "LuxCare Wash System" saying this: " Smart Load Sensing auto-adjusts based on the amount of clothes and water absorbency, because load size is a little more complicate[d] that [sic] just small, medium and large. " (Here is a link.)

It is curious that ELectrolux makes almost no other effort to explain it. I'm guessing that because "Load Sensing" is a common feature and operates automatically without any user input, their tech writers did not see any need to comment on it in the user manual. The company's web page for the EFLS627 (the current 600 series model) simply mentions that the machine has the LuxCare system and offers only the passing reference that LuxCare includes "smart load sensing" without bothering to explain it. Apparently, they expect you to find their LuxCare webpage to figure out what it is.

I think all frontloaders use the amount of water required. Mine is an old Frigidaire, and it uses less for small loads and more for large loads.

Frontloaders, like all washers for many years, have a water level pressure sensor that works by monitoring the level of water in the sump at the bottom of the outer tub.

The machine "wants" a specific level of water in the tub. Larger load, more clothes, more water is absorbed by the fabric ... so more water is needed to reach that level. Smaller load, less clothes, less water needed.

Sensors nowadays are electronic, and the programming on the machine's cycle control board can be designed for different sensor readings on the various cycles. Delicate and Bulky Items cycles typically fill higher than the designated Normal cycle.

"Old"-style toploaders had the pressure sensor connected to an adjustable switch that allowed the user to select various fill levels. Some older frontloaders (Westinghouse in the 1950s to 1970s comes to mind) also had adjustable levels but newfangled frontloaders nowadays are not directly adjustable by the user.

With modern front loaders smaller loads are not as easy to clean as you might think.

They need more clothes in the machine to help tumble more uniformly and to help more evenly distribute for spinning.

On my three year old Electrolux (WaveTouch series) if I have a really small load (microfiber car towels) I don't use the "add more water" option. Instead I use the Allergen with regular water option. When I use a "heated" cycle, less water is used (to heat it up faster). Otherwise the towels float on the water and never actually tumble.

I would include underwear in with your normal loads.

You have a large machine, you should use it and not do all these small loads...you're not making it easier on the machine or your time.