When I was a kid, we had to deal with neighbours parking their car on allocated spots. Not always the same car or neighbour. We had no choice but park way too far or on a rather illegal and insecure one. My dad's technique was, one day, to put a sign right in front of the spot. Something clearly identifying the spot as reserved. The only difference with your case is that it's reserved for a type of car and not a family. But the way to communicate can be pretty close.

In case you choose the sign, keep the idea "*clean and sharp*". Few words but explicit ones, leaving no room for confusion or doubt. Maybe with an extra EV icon. The spot is probably already marked as an EV spot, but people maybe don't pay attention (or don't care, like they do for family spots or disabled people's spots on mall's parkings...). Adding another sign kind of "*right in their face*" may bring light to the darkness. This is step one.

In our case (reserved spot #123 sign), it wasn't enough, so, with my dad, we used to write the license plate of the indelicate neighbour(s). 1 parking, 1 strike. At the second strike, he would leave a message kindly explaining that is was not an acceptable mistake and that this particular neighbour should be more careful. Note the words "*mistake*" and "*careful*" instead of "*don't give a ****" and "*respectful*". That's a smooth way to escalate I believe.

Finally, one time, on strike 3, he went and confronted the man. This time, it was more straight to the point and the guy was pissed and upset. Dad remained calm, as usual, but standed his ground and was clearly (in my kid's eyes) threatening that there would be no more trespassing. End of the story. 1 less friendly neighbour, if he ever was though...

So, in your case, I don't know how far you want to go and how hard you want to try but I'd really recommend doing small steps and starting with an impersonal sign, not targeting the offender. And then, according to the result, decide about step 2. If you have some sort of neighbours committee or board, whatever it's called, informing them is always an excellent idea, as they may inform all households. If this doesn't exists, I'd print your letter and put it in every mailbox around. It's still not targeting but is often efficient as people can realize they do something wrong and correct it without being caught. We didn't have this option in my dad's era :)