Audi is throwing a ton of incentives and promotional weight trying to unload the remaining B7 A4s before launching the B8 A4 so I bet the uptick in sales there is more reflective of that than people wanting to get into a smaller car.
Across the board sales are down as premium automakers are not going to be enticing people on the cusp in a downturn economy. Those folks will "settle" for the GTI instead of the A3.
Just my 2 cents (which are devaluating as I speak)...
'07 4.2 Q7, Light Silver/Black Leather, 3rd Row Seats, Cold Weather, 4-zone, Panorama Sunroof, Sirius and with 19" wheels
'01 allroad, Atlas Gray, 6-spd, RS6 Taillights, 3rd row