He later told his girlfriend Adriane Galisteu that he had not much liked driving the car Indy but had found it interesting.

Senna confided his excitement at driving the car to his friend and fellow Brazilian Fittipaldi. He says: “He liked the Penske very much. To my surprise, he said the suspension was quite stiff because he thought it would be softer than in a Formula One car. I could tell he was nervous to be on a new track and in a new car, but he was very enthusiastic about the whole thing. He was enjoying himself and he was very comfortable with the car. When he came into the garage after the first run his eyes were shining like a little boy with a new toy.”
He may have enjoyed the experience but perhaps he wasn’t being completely truthful with Fittipaldi. He later told his girlfriend Adriane Galisteu that he had not much liked driving the car after Formula One but had found it interesting.

SOURCE: The Life of Senna, page 324, chapter 23