It transpires the tip off we were given regardign the updates to the W01’s airbox was accurate, as Mercedes arrived in Barcelona with a radical new roll structure cum airbox. Even in its launch guise the W01 exhibited a unique pillar shaped roll structure with the non structural airbox wrapped around it. Now the team have further decoupled the airbox function from crash protection, by making the protection purely blade-like shape, with the airbox now formed totally by the engine cover and the inlet snorkels not touching the blade at all. This is a dramatic looking solution and probably worth some improved performance from the rear wing due to the decreased disturbance of the airflow. But in overall terms the change is only likely to be worth a small gain and not as important as the expected layout change or f-duct rear wing.
Scarbsf1's Blog 
I’ve been looking at other pictures of the update. One thing has caught my attention. I always thought the hole in the side of the airbox was an attempt to reduce the ‘ram air’ effect at high speed.
While they have maintained the hole – it is not at all connected to the air intake.
Of course, I could be wrong and the holes in the side of the air box are there for the sole purpose of lifting stricken/crashed cars from the circuit.
The hole is purely there to meet the legal requirement for a lifting eye, if ever the car needs to be winched off track.
I’m curious – with chassis homologation, and this being a vital part of the crash structure, how was this changed mid season?
As I mentioned the inlets are non structural, thus they are exempt from the crash test and homologation. In fact a lot of the visible surfaces behind the cockpit opening are bonded on panels, used for aerodynamic shaping, so these aren’t fitted for the crash test.
But the roll hoop (which has now been replaced with a roll “blade”) was structural?
@Dave Bauman:
Find some pictures taken form the front of the Mercedes, you will notice the ‘bridge’ is already in the tunnel. I guess no need for structural modifications there and probably already tested and approved.
You can see here what the crash structure looks like and has looked like since the launch http://www.motorsport-total.com/bilder/2010/100506/z1273149025.jpg
The airbox was just added on and wasn’t a structural part
Yep I see it now. I’d forgotten the original test image showed that the airbox was kind or additive because after the first few tests they added the side extra elements of bodywork underneath making it look more like a traditional airbox/rollhoop structure again.
@Dave Bauman
There was no roll hoop, the W01 always hat this central, blade-like roll structure.
I can’t be the only person who has looked at the blade and thought that if the car overturns in gravel or grass or any other soft surface it is going to cut through it like a knife. While a roll hoop will protect the driver’s head the blade on anything other than a hard sealed surface is going to be useless and the driver’s head and neck is liable to to be damaged.
I cannot believe it is a good idea to allow the roll over structure to be a blade rather than a hoop much as I appluad the innovation that has changed part of the car that has been fixed for decades.
You could argue that the same would happen if the car with the roll-hoop went in at an angle.