Mercedes team boss Ross Brawn says the new F1 W04 is a "clear step forward in design and detail sophistication over its predecessor, " while Lotus have continued their design themes with the E21, according to technical chief James Allison.

CNN: F1 revolution ahead after 'identikit' 2013 season

We went to Lotus, told them what we thought would work, and they came back with this design.

BBC: Polar express