Carlos Sainz says his first run in a Formula 1 car was the 'best day of his life'

A beaming Carlos Sainz could hardly hide his delight after getting his first experience in a Formula 1 car at Silverstone.

Sainz currently competes in GP3 with MW Arden and admits it was a massive leap to a Formula 1 car. "It is a very, very big change," he added. "Actually this test I was thinking that it was a good bench mark for me to asses my physical point of view - it was very important to see how good physically I am - and to be honest I am more tired when I got out of the car, my body has never had these feelings and is not used to the lateral G-Forces. "So for sure it is one of my tiredest days but I am pleased to say I never had to rest my neck or step out of the car to stretch. So in this sense I am happy as I didn't have any issues." On Friday Sainz switches to the sister Red Bull team and will drive the RB9 before handing over to triple World Champion Sebastian Vettel.