The click could be the hood mechanism - check the nuts are tightened.
Petrol smell is not something I ever noticed with my s4 in 2 years. You can get a petrol smell if the hood is up and you overfill the tank on an s2 or s3 but never had it on the s4 as the fuel tank is relocated.
Not sure about locking the bonnet, never thought anyone would try to open it, not much to steal under the hood anyway!
