My car generally exceeds its efficiency rating by around 15%.

The sort of alleged malfeasance is not normal. Edmund's claims most EVs meet or exceed their range estimates, while Tesla systematically inflates range estimates by a third.

Most of my ICEs and EVs reached advertised efficiency without much effort.

Let’s not normalize amount of deception Tesla does in their marketing and user hostile behaviors.

For many years, I got better-than-advertised mpg with a Honda Civic. My more recent vehicles, though, don't quite reach their claimed mpg. Is this "everyone lying" a new phenomenon, or is Honda an exception from "everyone"?

There is a difference between the range that a standardized test reports which allows for comparing apples to apples and a range that my car shows me based on my driving style.

When the missus drives the car and then fills up the tank I see range X. When I drive the car and fill up I see range Y. Different driving styles.

I frequently exceed it on mine as well as on rental cars. It really depends on one's driving style.

Coasting to upcoming red lights/stop signs and accelerating at a gentler pace make a big difference, as well as driving the speed limit on the highway.

I have. Perhaps not everyone?

I usually do a lot better than the advertised MPG on my Mazda