and that should be obvious right? Let's say you're familiar with how fast your car eats gas and you drive around on flats all the time.

When you take it into the mountains, it's not surprising that your gas gauge goes down a bit faster when you're pushing that gas pedal a little further than usual.

Perhaps the takeaway is that EVs shouldn't so prominently display the range as part of the "gas" gauge the way they tend to do.

I have it show percent, not range. Tesla defaults to percent on the main display. I'm not sure about other cars. When you use navigation then Tesla will show you the expected charge at your destination and it's been pretty accurate.

I drove my wife's Model 3 on a short trip from Sacramento, CA to Santa Cruz. 3.5hrs if you factor in traffic (2.5hrs without).

When we left, estimated range was 45% on arrival. We arrived with 27% range. Granted, we did encounter a crapload of traffic, but the Nav system took that into account because the time was accurate.

I don't fully fault Tesla for the range inaccuracy; an ICE car would probably have had a similar issue. But it's not as smart as I thought it was, which is a shame.

I obviously don’t have a reason why it was so off. We regularly drive from near sac to Santa Cruz and it’s within a few percent with plenty of speeding. I commute 100 miles a day on the freeway, so maybe it knows my freeway driving habits very well.

Doesn’t it know where it is ?

This goes to the optimistic/ exagerated calculation

Yeah. I’ve never had the car not know where it is.

It knows where it is. It can’t very well know which direction you want to go if you don’t tell it, can it.

Could it not take an elevation rate measure though?

Related to my other comment, it may be more difficult if it’s relying on weather station data rather than local car sensors though.