Romain Grosjean admits he is starting to lose patience with Renault after more problems during the Bahrain test.

Pastor Maldonado's running was cut short on Tuesday by an engine problem after 16 laps and Grosjean suffered exactly the same fate on Wednedsay as Lotus again struggled for mileage. Speaking to after his day was brought to an end, Grosjean admitted that faith in Renault was wavering slightly after further issues.

"I have to say that these two days have been quite tough on all of us," Grosjean said. "We were hoping for more, but again they say China or Barcelona will be a good step forward. Let's see...

"I think we are already quite a long way behind. With a perfect qualifying lap you're 16th on the grid which is not where we want to be. Today we did some aero tests with hopefully some good results that we can understand for China, a few things that we can maybe redesign, and then we just have to believe that Renault will be capable of bringing better performance and reliability because today was just not acceptable."

Explaining that his fastest lap came with only 75% of power, Grosjean said it wasn't even a repeat of the issue that stopped Maldonado on Tuesday which ended his own running.

"We struggled with the power unit all day long, never got the power we wanted and only managed a few laps. We fortunately did some aero laps and got some little information but compared to the programme we had planned today it's far from being done.

"It's been a different problem. Yesterday I was not aware of everything that was happening but today we had a problem with engine from the beginning of the day and then some more problems came on top of it and that was the day. Everything was engine today."