why didn't they keep the exhausts embedded in the bumper as they were in the concept. that looked so nice

 

This is because exhaust systems tend to heat up quickly and putting the metal exhaust outlet in an enclosed space like that is generally a formula for a melted portion of plastic bumper. It's just not a great way to implement the exhaust system in the real world though it does make for cleaner designs on concept cars.

 

that was what i was thinkin thanx for the explanation