Red Bull junior Pierre Gasly explained that there is little difference between the Red Bull RB11 and Toro Rosso STR10 after the French driver tested both cars at the Circuit de Barcelona-Catalunya.
Gasly sampled the Toro Rosso on Tuesday - his first experience in a Formula 1 car - before moving to the senior squad for Wednesday's running, during which he posted to third best time.
"To be honest, the difference is really small," he said when asked to compare the two Renault-powered outfits.
"In terms of lap time it is pretty much the same. So there were some small differences but also the conditions [on Wednesday] were a bit different to [Tuesday] - the wind was not in the same way.
"So we need to check the data further to understand a bit why the balance was like that, but overall I felt a bit better in the car."
GP2 driver Gasly added that he improved with confidence as the test developed.
"I also had a bit more experience and knew a bit better what to do," he said.
"I improved my lap time, my driving and also my feeling in the car. Overall I felt better, so I am pretty happy about it, and about the balance of the car, I would say it is very similar between the two cars."