Team-BHP - why swift faster than esteem?

I think its the aerodynamics of Swift !!. I have noticed definite difference in the cruising when I keep the windows rolled up when compared to keeping the windows open. Also another observation is reg. the hits the body sides take from small stones on the road as if they are getting sucked into a vortex !!
Unfortunately for all the fine design and the engine power, the metal gauge used by Maruti in the Swift is very poor and a small amount of pressure dents it. Another bad experience over the weekend when I used my Swift to carry a sack full of groceries ( in the dicky ). When my servant took it out he must have grazed the bumper part on the top side. I find the paint grazed and the black part visibile ( bumper is silky silver).