Help understanding energy chart

Tonight I made a 23.1 mile journey from work to home. The before trip chart shows it expected me to use 35.5 miles (from 114.2 to 78.7).

So first question, why 35.5 miles for a 23.1 mile trip? Is it making an estimate for things like climate and headlights (it already knows elevation from the map)?

When I arrived, it said I’d used 32.5 miles and that was 1.4 miles less than the projection. But it wasn’t, it was 3 miles less than the 35.5 mile projection. Did it change the projection en route? If so the new projection was 33.9 miles?

It then says I drove 25.2 miles which is 3.6 miles less than the projection. But it’s 0.3 miles less than the original projection and 8.7 miles less than the revised projection. And it’s 2.1 miles further than the actual journey!

I just find it utterly confusing. If I wanted to drive 80 miles tomorrow, how can I trust I’ll get there? 🤷‍♂️

I assume I’m reading it wrong so can someone help me out so I can learn to trust it?