Toro Rosso clarifies it is running a 2016 F1 car in testing

Carlos Sainz Jr said on Wednesday the car was "a mix of last year and some parts from this year" and later added "it's an STR10 with parts of STR11".

But Key said it is a completely new car apart from two parts that will be replaced, as had been scheduled, at the second test next week.

"It's definitely this year's car," told Autosport. "There are two carryover bits there on a temporary basis because the new bits are coming for the next test.

"Those are the only bits of 2015 we have on the car.

"We were quite happy with the chassis last year, we made a big step, so you want to keep strengths of what was working last year.

"The bodywork is very tight. That was an evolution of what we did last year, but other areas are completely different.

"The front suspension is very different, as is the nose.

"We have a blown front axle as Red Bull, Ferrari and McLaren have.

"That is not an obvious tool to add but the sort which appears to work for us and has allowed a new avenue of development which hasn't worked for us before.

"There are bits under the skin which are different as well."

As with most teams, Toro Rosso plans to bring new parts to the second test, which starts on Tuesday, where it will also officially unveil the STR11 and its 2016 colour scheme.

"I won't go into specifics but it's all performance-related parts," he said.

"There are some aero developments and some chassis developments under the skin."