^^^This, Always tell them you had nothing to drink. Because if you tell them you had just one beer then they can search your vehicle and do sobriety tests and all that good stuff.
Had a cop pull me over one time for brushing up on the curb going through downtown Clemson. I was trying to plug my ipod up, i had not been drinking... He lit me up after i got through downtown, so i pulled over. He comes up asks if i had been drinking i say no blah blah explain what happened. He made me an my buddy get out of the truck. So the cop asks can i search your truck? I didn't no any better at the time so i agreed. At the time i had shotgun shells in the back some knifes a empty gun case an some other things.. Turns out he was looking for any sort of firearm because thats a felony charge and he was trying to get me on that since i was not drunk. I would have been kicked out of Clemson an received a nice felony charge. Thank God my shotgun was not back there. When he found no gun back there he tried to tell me i was speeding i said nah man i was actually going the speed limit, he then tried to tell me i ran the redlight and i told him again nahh man it was yellow. He let me off wiith an "improper lane change". Moral of story? Don't tell the cops shit