I never trust anything from a big company. I always look at independent tests. If you bought computer hardware based on manufacturer lies you would think you had faulty hardware every time. If you buy food and drinks or medicine based on manufacturer advertising you would think you were sold counterfeit items. Always be skeptical and always verify independently where possible.
There are a lot of independent tests now where different cars are taken to a road and driven at the same time until the battery runs out. Then you get a decent real world example of what the vehicles are capable of. Also with nice direct comparisons to other manufacturers which is nice.
Use google translate or something if you would like to read, but basically this is a third party test of electric cars that test during summer and winter which is highly relevant for me. and Tesla occupies 2 of the top 3 spots.
*Edit: I actually misread the test. Tesla occupies 3 of the top 3 spots. With a Model S, a Model 3, and then another older Model S.
If I go to buy a new Model 3 Long Range on Teslas homepage right now I get 602 km range estimate. The independent test drove it 654.9 km on a sunny day. It got 514.8 km on a winter day. Winter days in Norway can get quite cold. I would feel quite comfortable buying a Tesla based on this test.
Tesla could say their cars could fly for all I care. The fact is that the Model 3 in this test comes very close to a Mercedes Benz EQS 580 in range. That is supremely impressive. Even if the Model 3 is a lot lighter and less comfortable to drive the range is very impressive for a car that is about a third of the price.