Toro Rosso has admitted time was so tight in the winter that a livery for the 2016 car had to be put on the backburner.
"We just ran out of time," technical boss James Key smiled in Barcelona, as the plain-blue STR11 was tested by Max Verstappen.
The Faenza based team said the full livery will be revealed on 1 March.
"We had three months to make a car," Key is quoted by Auto Motor und Sport. "Normally, you can’t do that."
Toro Rosso’s plans were thrown into disarray by the last-minute decision late last year to switch from Renault to 2015-specification Ferrari power.
Key said: "Just two months ago I could not imagine that we could be ready here in Barcelona."
150 extra staff were hired at Faenza, he confirmed.
"We had to make a few compromises with the (engine) installation," Key admitted.
But that does not mean the team is not expecting to be fast in 2016, with Key having even referred to a one second per lap boost compared to last year.
"Let’s hope so," said Verstappen’s father Jos. "But let’s not forget that the other teams are not standing still," he told verstappen.nl.
Max was dead last on the timesheets on Tuesday, but he insists the car is good, particularly in the horse power department.
"I can feel more power and my helmet being pulled up more by the wind," said the teenager, contrasting the new Ferrari grunt with the Renault of 2015.