Book/story where people are living in a collective illusion and the real world is crap [duplicate]

Question

At some point of the story, the main character encounters this scientist that gives him some mechanism (a drug, or some kind of mask that filters the element that creates the illusion) that allows him to see the real world and, for example, people are pretending to be driving cars but in reality they are just walking around.

At some point of the story the main character takes a more powerful version of this drug/filter and looks at the scientist, and his body, that had recently undergone surgery, is just a mess of tubes and pipes.

I probably read it like 10 years ago, it was either a short book or just a sci-fi story.

I think I saw later a movie based on this story/book, where they mix real people with animation, starts with a woman driving a convertible in the desert and when he approaches this complex, at some point cartoons and fantasy stuff start to pop out.

Answer 1

This is almost certainly Stanisław Lem’s The Futurological Congress. From the Wikipedia summary:

The professor then gives Tichy a flask of "up'n'at'm, one of the vigilanimides, a powerful countersomniac and antipsychem agent. A derivative of dimethylethylhexabutylpeptopeyotine". With his first sniff of up'n'at'm, Tichy watches as the gilded surroundings of the five-star restaurant they are in evaporates into a dingy concrete bunker, and his stuffed pheasant turns into "the most unappetizing gray-brown gruel, which stuck in globs to my tin — no longer silver — fork".

But this first dose is just the beginning of Tichy's journey. He sees that people do not drive cars or ride in elevators, but they run in the streets and climb the walls of empty elevator shafts, which explains why everyone in this new world is so out of breath. Robots whip people in the street and protect order. Through successive doses of more and more powerful types of up'n'at'm, Tichy sees increasingly horrible visions of the world, climaxing in a frozen horrorscape where people sleep blissfully in the snow, and the police robots are revealed to be people who are convinced that they are robots. The frozen state of the world explains why he has always found the new world to be so cold.

(I read this many years ago, and recall the scene you’re referring to with respect to the Professor being “a mess of tubes and pipes”, although it’s not at all mentioned in the summary).