Fernando Alonso's verdict on his first Indy 500 test

The McLaren Formula 1 driver completed 110 laps during his private test at the speedway, marking his first time behind the wheel of an IndyCar and his first running on an oval.

Alonso, who completed the mandatory rookie orientation programme in his first hour on track, set a fastest lap speed of 222.548mph, and he said he ended the day with respect for the venue.

"The track is narrower than I thought," he told the media after finishing his test.

"You watch the television and you see three cars alongside on the main straight - now I am in the car on the main straight and it's hard to imagine how you can fit three cars there at speed.

"I knew that Marco [Andretti, who shook the car down in the morning] was flat out in Turn 1, so I said I will do Turn 1 flat out because I know that the car is able to do it.

"I arrived in Turn 1 and I was convinced that I was doing flat out, but the foot was not flat - it had its own life, it was not connected to my brain at that moment.

"On the second or third lap I was able to do it, but on the first lap it was definitely a very good feeling to be able to feel the respect of the place, the respect of the car, the respect of the speed.

"For any racing driver that feeling is pure adrenaline, so it was a good day."

Once Alonso had used up his allocation of fresh tyres, the Andretti Autosport team experimented with some basic set-up changes, as well as a programme that included caution period simulations, fuel milage tests and practice at entering and exiting the pits.

Alonso said he enjoyed the simplicity of operating an IndyCar machine, which enabled him to get through the team's desired programme quickly.

"They ask you if you are ready inside the car, you say yes, you switch on the car and you go," he said.

"In Formula 1 it takes maybe six minutes to fire up the car, because they need to check, recheck, there is so much technology there.

"Many things slow down every run. Here, it's more fun because you just switch on the engine and you race."

Alonso was asked for feedback between runs by his engineers, but he said he did not yet feel qualified to judge the car and the conditions with authority after his first day on an oval.

"The team was asking me about it, and I feel good, but I have no idea, no experience of when the circuit is good or bad, or when the circuit is fast or slow," he said.

"The team has been very supportive, and now we have a lot more things to go through that will be more useful.

"There is still a long way to go but I'm happy with the first step."