i've been told this one, be it a myth or not but the officer has to be a senior Sargent or to that affect to have an uncontested look under your bonnet. A friends work colleague used this to avoid it but he probably had a lot to loose if defected so it was a chance he was willing to take. That said if you give permission to look for a lower ranked officer then that's enough for them. But as someone said before, your probably gonna be in a bigger world of hurt if you don't comply robo-cop style.
Last time i got pulled over was 3 months ago in knox right infront of the cop shop. was stopping at the red light saw a persuit car waiting to exit the cop station and low and behold the pulled up right behind me..ha didnt make it 50m lol. They were good about it, i got out of the car as I always do and complied with their requests. Wasn't the typical muzza with attitude that they normally encounter and that was that. Was expecting an exhaust epa in the mail....still have yet to receive it so i guess they gave me the benefit of the doubt?