Have my first Subaru. 2005 Forester. When coasting down hill by my home my former car, Toyota Camry, would increase speed by 10 mph by time I got to bottom. My Forester only increases about 3 mph in same distance and at same starting speed. Is this due to AWD system, or is it possible brakes are draging or something like that ?

Is it broken in yet? New vehicles are "tight" mechanically until they get a few thousand miles on them. That's why you need to break in a new engine. Transmission, drivetrain and brakes, when new, could all create a "drag" on momentum.

Don't forget there's a fair weight difference between a Camry (erghhhh....cardigan car.....) and a Forester, so gravity could have something to do with it.

Is your Forester MT or AT? The different shift points etc in the 2 cars may also contribute. I have found that my 02 AT OBW "holds" 3rd or 4th coasting downhill a long time before the torque converter locks up and the car coasts "free".

different aerodinamics may play a role but I bet (if the cars are AT) different setting in tranny computers affect how effective engine braking you see in diffrent cars. Also, bigger engine may contribute a greater braking too. In summary, who knows?

and you are rolling a four wheel drive system. Huge difference in coasting with my tiny BMW roadster and my Forrester. To be expected.

The forestor has the aerodynamics of a brick or a school bus (tall and square like old Volvos)...I bet that has something to do with it. Plus a little bit can be attributed to the AWD.

Parisitic drag doesn't really come into play until you're over sixty or so. So, on the interstate you may feel aerodrag, going down deadman's hill in your local neighborhood, not.

Have you checked the underside to see if you have hit anyone and their lifeless body is slowing you down.