My first thought to preserve the looks as much as possible was to install clear plastic panels between the spokes and flush to the surface, but unfortunately looking at the 2012 stock wheels it looks like you'd end up with a concave surface... thinking that's not a good aero idea
Vekke has used polycarbonate transparent hubcaps on his VW for a while
They're green translucent though, his Tuneko commercial site has a good pic of clear ones and their effect on the look of the wheel.
Link