>Going uphill on mountains means you're going downhill which not only doesn't use power but regenerates power to the battery.

If you are pulling a trailer (let's say a camping trailer) you are likely going to stay a few days at a place before returning home and going down those hills you went up.

That's OK. It's not like the potential energy goes away just because you stay overnight. Plus there's a solar panel for all that power you are going to use while making hot toddies in the camper.

You vastly overestimate solar power. There’s no way you’ll get an appreciable charge on your Tesla battery using solar panels. It’s enough to run things in your trailer, but no way will you charge a Tesla in any reasonable time. I suppose if you are stranded with no way to charge you could get enough to go somewhere after a few days of constant charging, but that’s an emergency situation.

I guess, but I've never driven 100 miles up a mountain to stay for a few days.

From Vancouver (sea level) to Whistler is 7000 ft but only 80 miles. I wonder if you could pull a trailer up that height and over that distance.

> It's obviously not insignificant of a cost but adding a trailer doesn't immediately halve the usable range.

It probably would through aerodynamic drag at the same speed but if you're planning on towing you can just drive slower (65 instead of 80) to make up for it.

> Going uphill on mountains means you're going downhill

Not if the mountain's big enough. You might only go an appreciable distance downhill on the way home.

Barring something like a city decimating earthquake - for every foot you ascend, you must also descend. There is just as much uphill as downhill. This is true for any trip with any two destinations on the planet (a round trip between a beginning and a destination). This is equivalent to conservation of potential energy in physics.

There are a lot of mountains in the US where you're going to spend hours driving up steep inclines. I used to live on the wrong end of a 2 hour uphill drive with one gas station in the middle. That road was steep enough that even a gasoline car couldn't make the trip without a full tank of gas.

Your comment makes you sound like a city boy.

I drive through mountains all the time, and have to fill up my car all the time. GP didn't say anything about multiple stops; what I inferred (because it's literally what he said) was that you can have unequal ascending and descending on a round trip - which is geometrically impossible! And even if we are talking about having to stop and get gas, you still get the same benefit of regenerative braking when you are descending, whether it be the first half or the second half of the trip.

> Your comment makes you sound like a city boy.

Is this supposed to be an insult?

Around where I live the preferred term is "cidiot". I find it to be refreshingly creative.

Ontario, Canada?

Or maybe it’s generally a midwestern North America thing?

Then that means that you stopped somewhere along the way.

Have you never been up a mountain? You can go up one very steep portion at 45 degree incline and then come out the other side going on a very long down hill at like 5 degree decline, basically flat.

It doesn't matter. The battery is still regenerating on the way down until you're back at the start point. A less steep angle might even be better because there's no potential to lose energy since the battery can only regen so much at a given time.

On less steep inclines the car still has to do more work to move it’s wheels at a desired speed, even if gravity helps.

My truck goes from 22 mpg to 10 mpg when I hook up my RV. Utility trailers aren't nearly so bad, but an RV trailer is like an open parachute behind you.