^ you aren't looking at the fact that subaru has the highest mpg awd vehicle on the market right now...AND...even with that title, it still has 150hp (which btw has better hp per cylinder numbers than the example 200hp V6 from toyota you mentioned...37.5hp/cyl vs 33.3hp/cyl). also, even though power dropped 20hp over the previous impreza and mpg improved almost 10mpg, it is faster in pretty much every way.
EDIT: just looked up nissan and toyota 2.5L V6's.
toyota DOESN'T have a 2.5L V6 in anything currently...at least i couldn't find one. nissan has the VQ25DE, but that engine is only putting out 178hp in the 2010 models (which btw is ONLY used in the 2010 Renault cars). soo...not sure where you got this 200hp example from, but sounds to me like subaru is doing JUST fine.
as for the 2013 RDX, it actually is a decent comparison to the 2013 forester. the forester is actually slightly larger than the RDX in the cargo area, but slightly smaller than the RDX in the leg room area. the forester x has lower performance than the RDX specs, but it gets basically the same mpg. the forester XT is about the same as the RDX performance specs, but slightly less mpg on the highway (pretty much the same mpg city though). so...doesn't sound like subaru is really too far behind here either considering the forester has had pretty much the same specs since 2009...and lets not forget that the forester starts about $15,000 cheaper than the base AWD RDX. the base AWD RDX is the same price as a fully loaded XT Premium.