[NeilBlanchard]

Hi,

I've done a coast down test on my xA, and yes finding a flat straight road is the hard part. It does not have to be level, as long as it is a low slope -- it just can't have a dip or rise in it.

The other major piece of guesswork is the tire rolling resistance.

My best estimate based on 0.011 Crr (which is on the low end of "normal tires on smooth roads"), is 0.27Cd. (The stock rating is 0.31, though my car is a RS 2.0 that has a far more open grill than the standard xA.)

BTW, my average terminal speed after 70 seconds (starting at 70kph/43.5mph) is 27kph/16.7mph.

[Edit: At the time I did the coast down test I had the grill blocks, fog light covers, zigzag tape on A-pillars, top of the windshield, backs of mirrors, and trailing edge around the hatch, I had the rear wheel skirts, and the underpan under the hatch area, and the mini-Kamm panels.

Since doing the coast down test, I added the front wheel skirts, the video mirrors (which also reduces the frontal area), and I have lost the rear underpan. I hope to rerun the coast down test before I have to replace my tires...]