Horner hails positive RB8 debut after first day of F1 testing at Jerez

Although it is too early to read anything into the overall laptimes, with Mark Webber fourth fastest, eight tenths of a second off Lotus driver Kimi Raikkonen, Horner was encouraged that the RB8 was performing as hoped.

"It has been a positive first day," said Horner when asked by AUTOSPORT whether the car was performing as expected. "There is not too much to read into it, but the initial signs are that the car has behaved as expected. Our team is pretty pleased with its first day back in the office.

"It's difficult to predict where you are compared to your rivals. We're trying to ignore the timing screens at the moment and focus very much on our own programme."

Webber completed 53 laps after the team's start was delayed because the rear wing assembly was late arriving at the circuit.

Despite that, the team completed all the typical day one systems check running that it had planned.

"We got off to a slowish start waiting for some components with the rear wing that got delayed a little bit due to the fog in Jerez," said Horner. "The plane got diverted to Seville.

"After that, we got into a programme ticking off all of the new car stuff that you need to go to. It was a positive first day for RB8 and we have a lot of valuable data to go through."