The Mercedes challenge stepped up a gear when Nico Rosberg won convincingly in China, but the W03’s form has since been erratic.
Michael Schumacher has put in some good qualifying performances, especially in the wet, but third place in Valencia was the exception to a run of tough luck on Sundays. Over the coming weeks there will be increasing interest in his future plans.
Williams and Sauber have also been inconsistent, but both have proved they can fight at the front on their day. It remains to be seen whether they can do that as the development race intensifies.