A fair amount of that may be down to wiring, if you want all the extra toys you get in new cars you need a lot of copper to connect it all together. I know Subaru aren't re-known for their creature comforts but all the safety feature like air bags and the associated electronics all add to the cars weight.
Cheapest and easiest way to decrease the weight is put the driver on a diet, if I did that I could knock 2 seconds off my 0-60 time
