F1 driver Romain Grosjean's NASCAR hopes on hold until 2017

Last month Grosjean declared serious intent of making a guest appearance in the series with the Haas F1 team's sister outfit Stewart-Haas racing.

Grosjean recognises, however, his chances of a drive this year are now limited, with the race at Watkins Glen on August 7, during the F1 summer break, his only realistic possibility.

But with six grands prix over the next eight weekends before the break begins, Grosjean now feels his best opportunity to prepare properly is to wait until next year.

"I'm going to two races - Kansas [October 16] and Homestead [November 20] - as a spectator," said Grosjean.

"In terms of racing the only choice we have now is Watkins Glen in the August break, but it's a bit tricky during that.

"If it's not this year then I will practice over the winter, and next year we will definitely put it on the calendar.

"Yes, I want to do it, but it doesn't fit very well with the schedule, so its either Watkins Glen or next year.

"But I want to get in some days of testing. It's pointless being there to be last."

Asked about the likelihood of testing given the F1 schedule, Grosjean added: "January/February is the only time we've got a chance to do something, somewhere in the American south where it's hot and you can test.

"As for testing this year, it would have to be the end of June, but that would mean five race weekends in a row, so it's tricky."

Suggested to Grosjean it was probably too late to drive this year, he replied: "If the team really wants then we will do it.

"But it's more likely [it will be] in the future."

No updated power unit for Haas in Canada

Haas, meanwhile, will have to wait to receive the updated engine Ferrari is using for this weekend's race in Canada.

Ferrari has spent two development tokens on upgrading the turbo on its engine, but only Sebastian Vettel and Kimi Raikkonen will enjoy the system, with customers Haas and Sauber having to wait.

Grosjean said: "It's good they [Ferrari] are working hard, but they bring it [the new engine] at the last minute.

"It will come, not for Baku [next weekend]. It depends on our engine plans if we want to change things, but it will come soon."