Caterham arrived after the summer break looking to chase down their closest advisory: Marussia. With this in mind the new owners had given a raft of new performance parts the green light as they chase their rivals for the all important 10th place. (Although Marussia are currently in 9th, owing to a bad season for Sauber)
Part of the upgrade package was a new engine cover/cooling outlet, which looks to make better use of the region, not only by dispatching of the un-wanted latent powerunit heat but also by improving airflow, especially in the coke bottle region.
Also worth noting is the new paint scheme on the Caterham, dropping the mixture of Green, White and Black down to just Black might not seem like a huge weight saving but every little matters. Furthermore this is a recognized Colin Kolles tactic (weight reduction) in order to gain competitiveness.