Fernando Alonso says driving in the car in which he will contest the Indy500 feels more pure than a Formula One car, comparing the experience to his karting days.

Alonso is to miss the Monaco Grand Prix in order to compete in Indianapolis for McLaren-Honda-Andretti on May 28.

There were positive signs for the Spaniard, who has spoken of his desire to complete the triple crown of winning the Monaco Grand Prix, the Indy 500 and 24 Hours of Le Mans, as he was fourth fastest in practice on Wednesday.

Writing for the Players' Tribune, the two-time F1 world champion said: "I am back to doing what I love again, learning. Everyone - from the team at McLaren-Honda-Andretti, to the people I've met during my time in America - has been so helpful.

"It's hard to miss the Monaco Grand Prix, but the tradition at Indy is tremendous as well. I keep hearing about it from everyone I speak with. I can't wait for the pre-race ceremonies and the atmosphere. Here I am, a veteran driver, but it's all brand new to me. The anthem, the circuit, the racing - I'm very thankful to experience it. 

"I'm going to try and enjoy my time outside the car as much as I can. Because once race weekend comes around, it's go time.

"Thanks to the simulator testing, I felt like I knew my car before I got in it last week at Indy. But once I did, there was one thing that nothing could have prepared me for: the raw, unfiltered feeling of power. 

"Indy cars are a little more simple than the F1 cars, so it's more pure. There's less mechanical grip here, so the throttle has a bit more punch. It took a little time to get comfortable, but the team did a great job preparing me. My biggest takeaway from being behind the wheel was just sheer excitement. I can't wait for May 28.

"Like my first go-kart, this car wasn't built for me. I'm not the intended driver, but I'm going to do everything I can to make the people who built it proud. And maybe this will be the start of a new journey for me as well.

"And I want to make something clear. I'm not coming for a "week off" or to just have fun — I am a racer, I am coming to race. Above all, I hope this is an experience I can take with me for the rest of my life. I hope the feelings I feel, and the things I see stay in my mind forever.

"And I hope that at the end of those 500 miles, I've learned something that I never knew before."