Re: Sport Mode
If it stayed in Sport mode at key cycle it would have messed up the EPA mileage numbers. Testing requires that the "default" configuration be used for such things, and if the "default" was whatever you left it in, they'd have likely lost a couple mpg (if it does indeed raise shift points and increase throttle sensitivity as it seems to do, efficiency drops). Despite the claims of some, those numbers matter in the marketplace. Therefore, default is AUTO.
As for tire wear, if anything, I'd expect reduced tread wear on the front tires, since they are asked to do less (they aren't handling as much power). However, this reduction would be very minor and likely completely unnoticeable.