Does anyone have one of these AP22 meters from Race-Technology? If so what value do you use for the CDA of the Impreza (the air drag factor for the Impreza)? It's important to get this right to get consistent power readings in different gears. It's a great device and gives very accurate 0-60, quarter mile times, power, etc..
Cheers

 

The cartest.zip program I have lists the following for a US Impreza 2.5 RS (same body style, from the front anyway).

Cd: 0.36
Overall height: 1410 mm
Overall width: 1704 mm
Tyre width: 205 mm
Ground clearance: 145 mm

So the frontal area is a box that is (overall height)*(overall width), plus two boxes sticking out of the bottom that are (tyre width)*(ground clearance). I make that (1410*1704)+2*(205*145) = 2,462,090 mm^2 or 2.462 m^2

Since this is now in SI units, I assume that CdA is just Cd (dimensionless number) multiplied by frontal area (m^2) which gives 0.8863 m^2 as a figure for CdA. Does this look like a reasonable number?

 

Thanks Carl - I've been using something around 0.85 from coasting tests but it's difficult to find a long flat road with little traffic for this sort of thing (!). I'm sure your calc is correct, as you say CDA = CD times A - thanks very much for the numbers as I don't have this data.