First of all, the famous Einstein's elevator experiment is quite clear in my head, both of versions.
But now, consider the following:
Suppose then you wake up inside a car that is traveling in perfect straight path in a autoban (but you don't know that). The car have a constant velocity $v$ and is a self-driving car with totally dark-glass windows. You don't have any information about the outside world. After a time $t$ travelling in the straight path, the car enters in a curve. You then fells an acceleration (exactly with $9,8 m/s^2$) accelerating you.
Now, in my opinion, the person inside the car cannot say that the centrifugal acceleration is different from artificial constant gravitational field. The equivalence principle states something similar, since a person inside a elevator in a gravitational field is equivalent to a person inside a elevator which is accelerated with $9,8 m/s^2$. Furthermore, we can construct a ring-like structure to produce, via circular motion, a artificial gravitational field.
So, can I say that any accelerated frame, due to equivalence principle, is equivalent to a gravitational field?