Jenson Button and Fernando Alonso admitted they were surprised to be able to fight with other cars during the Malaysian Grand Prix.
Both the Briton and the Spaniard retired from the Sepang event, but they were close to the Toro Rossos and the Red Bulls before they had to pull out of the race.
Button had to retire due to a problem with the turbo, while Alonso had ERS issues.
But both men said they were encouraged by the step forward made by McLaren.
"I enjoyed it out there. It's nice to race against other cars," said Button. "To be able to see a Red Bull so far into the race was a surprise.
"They were obviously held up by other cars, but we were able to mix it a little bit more today so it's a good step forward.
"We were actually racing people. You can see where our strengths and our weaknesses are.
"Useful day, it's just a pity we both ended up finishing early."
Alonso added: "It wasn't too bad. I had a Red Bull and a Toro Rosso in front and I was catching them once I passed Perez, so it was a bit of a surprise to run with the rest of the cars."