Grosjean's time in F1 came to a premature end after his horrific crash at the Bahrain Grand Prix last year.
Due to injuries sustained to his hands, the Frenchman was unable to take part in what should have been his final two races in Sakhir and Abu Dhabi.
After the crash, Mercedes team principal Toto Wolff said he would offer Grosjean a test if the driver was keen to return to the cockpit, an offer which will come to fruition after the French GP weekend at Paul Ricard, despite the recently announced date change.
Speaking on the 'Beyond the Grid' podcast, Grosjean explained: “I would say it is the cherry on the cake.
"As I say, my chapter in Formula 1 has been over and many people texted me at the first race of the season ‘Oh it must be so hard to watch,’ and I was like ‘No. It’s actually cool.’.
“I’m enjoying watching the race. It’s a good fight between Max and Lewis for who is going to win. It’s quite exciting. The midfield is super tight.
“I’m happy watching it and I don’t have any hard feelings for it because my chapter, I feel, is done but obviously having an extra day in the car like the Mercedes for fun, for myself, that is incredible.”
Asked if he had received any advice from Lewis Hamilton or Valtteri Bottas, Grosjean added: “No, I haven’t got any yet. I guess they have been fairly busy fighting cars.
"But I had a chance to get a few laps on the simulator and seemed to be doing alright. I haven’t forgotten how to race a car. My neck may not be so happy but that is another story.”
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