Weight and drag coefficient play a big role. Tesla has really taken care to optimize their cars structure to reduce weight where possible. Thats why the battery box is a structural part of the car. This results in having to move less mass, which means there is not as great a need for a large battery, which in turn reduces mass. Add on top a “slippery” car and efficient power train and you get a result of managing to drive further with less.

Although it is prudent to point out that the WLTP claims are not always very accurate and can be nudged by manufacturers quite a bit. Take the Porche Taycan for example which generally gets more than the WLTP vs any Tesla which usually get less even if you drive them past 0 unless it is really perfect weather conditions.

I got lucky, got one from the first quarter production and have had pretty much no issues (needed some earlier than preferred bushings replaced but had that done during regular visits so no special visits). But the software is buggy (not unusable) and as far as I have heard that is still the case for the newest ones off the line, 2 years later, as well.