Sutil: Too much weight in car
Adrian Sutil fears there may be no end in sight to what he has described as his most difficult start to a season.
Sutil is without a point since joining Sauber, and has retired on three occasions in the opening five grands prix.
To add to Sutil's woes, the German remarkably remains on a diet given his current car continues to struggle with weight issues compared to their rivals.
Since the Bahrain Grand Prix seven weeks ago, not only has Sutil shed weight, but he has confirmed the car has lost at least 10 kilograms - yet that is still not enough.
"The car is still carrying a bit too much weight for my situation," Sutil said.
"We reduced it quite a lot from Bahrain to Barcelona (for the Spanish Grand Prix). It was a good step in weight-reduction.
"We've lost more than 10 kilos, which means you are three to four tenths (of a second) quicker depending on the circuit.
"Whenever you go out you are 0.4 seconds faster - it doesn't matter what you do.
"But I'm still heavier, and still on a diet, whereas Esteban (team-mate Gutierrez) is now fine.
"Obviously the lighter you are the better because then you can place some of the weight where you need it (on the car).
"We are talking about a few more kilos, but I don't want to say a definite number. It's still quite a bit we have to find.
"The best situation is having another five to 10 kilos to play with and then you can really place it where you need it. Then you are in a good area.
"So we need to wait a little longer and reduce the weight quite a lot."
It means the last few months have been a nightmare scenario for the 31-year-old German, who spent six of his previous seven years in F1 with Force India prior to joining Sauber.
"After the first two (pre-season) tests I thought it was going to be a hard start," Sutil added.
"You always try to think in a positive way, but I had a few worries before the first race, to be honest.
"We were not ready and the car from the driveability (point of view) was not where it should have been. We could see that from the first test.
"Still, it's where we are at the moment and we have to try to improve and make it better.
"But this has definitely been one of the most difficult starts (to a season), and it's very difficult to get out of it at the moment."