You should give more specs
You should give more specs for perspective. No, it is not a fast car, but I did find the power to be adequate when I drove one. Rev it. It goes! Unless you are drag racing it, it moves well. You have to remember the object of this kind of car. This is a "city car", mainly for the city and suburbs, with the occasional highway stint. It's not designed or intended to be a highway cruiser. The 500C starts around $19K - not $24. Unless you are a big person, I don't understand what you mean about pressed against the door. I am an average sized man (about 6ft /170lbs), and I had plenty of shoulder and hip room when I test drove two of them. Yes, the cabin is narrowish, but not as much so as a small car from the early 90s and before.
As for the EPA estimate, experience has shown that the estimage is very conservative. A friend of mine with a manual has been getting low 40s on the highway and mid 30's combined. Not fantastic, but it beats just about anything else on the American road.