1. On road trip, you rarely ever can count on re-accessing (re-charging) the 90-100% capacity, simply because of the charge curves. It just takes forever to go through those in a way that it is not even efficient to wait for it. I doubt the majority of people knows what charge curves are. Anyway, let's say that the consumer can wait for that slow charging between 90 to 100% in the middle of a trip, the majority of luxury cars have lithium ion batteries and it's never advised to exceed 90%. In fact, research shows that even 80% (when possible) should be the limit to avoid degradation. Hence, there we go, 10% of immediate loss from the YouTubers and (my friend told me) standards; at least for me.
2. You would never ever want to aim to arrive with less than 15% at your destination. If you are on a trip, you need to always make sure there is a minimum of 15%. That 15% guarantees that you have enough charge to part over-night, navigate to a tire shop, have emergency 15%. Beside all of that, it is never advisable to let the charge level go below 15% on lithium ion batteries to avoid degradation. Hence, another 15% that are not within what I refer to as the "usable" range, combined with #1, that is 25%.
3. Driving on highway by itself is another 20% hit and I could care less about what YouTubers say with my firsthand experience. Most of the time we never drive at 65 mph in the US. From experience, all EVs have a HUGE range hit by just going from 70 to 75, or 75 to 85 MPH. In the US, most of the time I personally drive close to 78 MPH in a 75 MPH zone, etc etc. As you said, in real world, highway miles cause another 10-20% hit or so. On EVs that were designed to be an EV (low drag coefficient like EQS or Tesla cars) they tend to do better efficiency wise at high speed. EQS drag coefficient is 0.2. i7 because it was design as an Ice+EV has a compromised drag coefficient of 0.24. The impact of drag coefficient is minimal for in-town driving and speeds at or below 65MPH. However, I bet that for every 5MPH above 65 MPH that i7 would see a very serious drop in range even more than that of other EVs that are designed from day-1 to be a pure EV. The same is true for the i5 despite that I almost bought one.
4. Occasional trips against wind --> my tesla calculates 15% hit when I drive south against normal slow speed wind, although I get those back when I drive North back home, but I know that my range from home to my destination during the first route is already compromised, which I do compensate for it by charging to 90% at home instead of 80% as needed. I'd never do 100%, ever, period. Wind is a big deal, but am yet to also experience rain. I now have taken over 18 trips of 100+miles trips on my car, and did more than 50 trips with rental EVs I had in the past 3 months. They all acted the same on different highway routes (iX, i4, EQS, EQE, Model Y, Model S, Model X, Lucid).
5. WINTER TIME!!.. that's is the big hit.... at the very least I would say 10-20% (even conservetiivably) based on reports from others, and my personal experience says the same. Under very very harsh winter for those who live in areas wherein temp can drop to the 20-30 degF and lower, 25-45% drop is not that crazy to expect. recurrentauto is a very legit resource and shows i3 drop as ~25% in winter, Model S 4% though I've seen people reporting 20%, and Ford Mach-E as ~30%. That does not even factor in harsh winter on days below 20 degF or rain.
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