F1 testing: Why the 2015 cars are faster at Jerez

BBC pit-lane reporter Tom Clarkson explains why the 2015 F1 cars are around one-and-a-half seconds faster around the Jerez circuit than in 2014.

A combination of increased horsepower from the 2015 engine, as well as improvements in downforce, have meant that lap times in Spain have improved significantly from last year.

Follow all the stories from day three of testing here.

Available to UK users only.