It was Sloane's way to make Dixon pay for killing his wife and inflict the same amount of emotional pain of seeing his wife die in person (albeit in a spectacular fashion). I don't really understand the confusion, I thought the storytelling was clear enough. Please I swear I saw a smirk from the valet as he leaves from camera view. :D

Honestly after the wife drove off, I figured she was off view from the camera. The car that exploded looked like that little Volvo-y station wagon thingy that Dixon was driving.

I think that the clerk smirked as well. I don't know why Dixon got out of the car as well, but to me, it was obviously that Sloane was going after Dixon's wife. An eye for an eye type of deal.

well count me as shocked. thinking back, yes it was very obvious what would happen but for some reason i was surprised.