Good afternoon. So I saw a great way to check degredation (atleast what the vehicle calculates) w/o 3rd party apps. Take your vehicles EPA mileage (mine is a MYP = 303) then go on the tesla app in the top left and click so you see your percentage (mine = 75%). Take the 303 and multiply by 0.75 which equals = 227. Then click the top left of the app again to show mileage (mine = 225). So I've lost ~2 miles or less than 1% in 3k miles. Hope this helps. Post your results and current mileage!