Kiwi driver Brendon Hartley has clocked the eighth fastest time during a long and productive first day of official Formula One testing in Barcelona.
Hartley racked up 93 laps in his new-look Toro Rosso car, second only to Australian Daniel Ricciardo (105), who also recorded the fastest lap.
Hartley's best time of one minute 22.271 seconds was 2.192sec slower than his Red Bull Racing rival and only a fraction behind world champion Lewis Hamilton in a Mercedes.
A month out from the season-opening Australian Grand Prix in Melbourne, Hartley was delighted with the off-season strides made in a car which has switched from Renault to Honda engines.
"It was a really positive day. Getting through 93 laps on the first day of testing was a great start to the campaign," Hartley said.
"Balance-wise, we were pretty comfortable straight away but I still think there's potential to unlock.
"The driveability of the engine is one of the best I've driven in a Formula One car, so it was really positive in all aspects."
Hartley's teammate Pierre Gasly will run the car on day two of testing before the Kiwi returns to the seat on Wednesday.
Hartley made his Formula One debut last year, called in for the final four rounds by Toro Rosso, before signing a full-time contract.
He finished 13th on debut in the United States, failed to finish in Mexico and Brazil before a 15th-placed finale in Abu Dhabi.