The Mercedes F1 team fears it could be at a disadvantage to rivals Ferrari at Monaco this weekend.
Lewis Hamilton managed to overcome an early setback in Spain to win last time out. But his team mate Valtteri Bottas is worried that the W08 is not as well suited to the Monaco street circuit.
"A car with the longest wheelbase on a track with so many slow corners," Bottas told Brazil's Globo this week. "We could be slower than them."
The same issue was on Niki Lauda's mind.
"We will have our problems with our longest wheelbase through the tight corners," he conceded to Swiss publication Blick.
"It will be even worse than in Singapore," he added.
"We have new cars this weekend which are wider and faster," acknowledged Hamilton. "That's going to be a massive challenge.
"It'll be a real test of your awareness of where the car is. I'm sure there will be some brushing of the barriers," he predicted.
But it's not only the long wheelbase that is causing anxiety at Mercedes heading into Monaco. The power unit failure experienced by Bottas during the Spanish Grand Prix was also a matter of some concern.
"Reliability is important in every world championship," Lauda agreed.
"The turbo problem Bottas had in Barcelona hurts us. Now our well-known English-German quality control will have to improve.
"We do not want a world championship of technical failures," he added.
Team boss Toto Wolff confirmed that the team had identified the problem with Bottas' car in Barcelona.
"We haven't seen that defect before, which shows you that you need to be double diligent," he said.
"We expect Monaco to be a completely different ball game to Barcelona," he added. Not every factor is under your control.
"You need to turn fortune in your favour at the right time if you want everything to come together."
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