Renault adds extra mirror support
As reported earlier in this blog, Renault have integrated their rear view mirrors onto the sidepod panel. Ferrari gave the example of hiding the mirrors behind the front wheels in 2006 after which several teams adopted the idea in their 2007 competitors. The initial Renault design as it appeared at the launch and winter tests apparently proved a little too weak in order to maintain good driver visibility at high speeds. The team have therefore added a small extra support for the mirrors. Although little, this support is a slight aerodynamic handicap compared to the initial design.
it is naut cause of driver visibility... the mirrors were flexing and rival teams had pointed out that it was flexing too much. that is the only reason why the additional bars were added so that it did not flex under high speeds...
soem more can be read here about those mirro support
http://www.formula1.com/insight/technical_analysis/