"We ask for consent to search. That's our policy."Unfortunately, that policy has led to highly discriminatory outcomes. A study by the Steward Research Group (pdf) released last year found that Austin PD uses "consent search" tactics on black people 5.3 times more often than on whites, although they were roughly twice as likely to find contraband on whites as blacks. APD City manager Toby Futrell promised to lower the number of consent searches in Austin, but there's no evidence the department has done so, or is serious about reducing the number of discriminatory searches.
Mostly, Austin cops won't use drug dogs because Texas laws don't really allow drivers to say 'no' to a consent search. Most drivers, not knowing any better, consent anyway. But as described in the second half of this post, after the U.S. Supreme Court's decision in Atwater v. Lago Vista, Texas drivers can be arrested for mere traffic violations if they refuse consent to searches of their vehicles. Then, their car can be searched in the impound lot as part of an "inventory search." Most drivers, faced with those options, consent to a search of their vehicle.