Here is a question wondering if anyone else has experienced this? When I first start my car there is an exhaust rattle that occurs between 1500rpm-2200rpm. My car is brand new and has 3000 miles on it I took it to the dealership and the mechanic said that it was the flex pipe under the front of the vehicle and that it will rattle when it is cold because it expands and contracts. Anyone ever hear of this before? Thanks