You're Johnny J. Law (the "J" stands for justice) and you have carte blanche to spend your almost endless pool of Homeland Security money that would be better spent in a major metropolis to pick a vehicle to cruise your patch of jurisdiction somewhere in rural Arizona or along the Pacific Coastline (the terrorists hate sunsets). You could go with something already prepped for the job like a Charger police car or something with the novelty factor like a Bug-er-ceptor. Nothing says you're a bad ass more than a Bullitt Mustang.
Personally, we're big fans of the Texas DPS Mustang LX, which always got us excited when driving the state highways between Corpus Christi and Houston. If you're running short on ideas, here is a long list of intimidating police cars. Oh, and if you're not worried about running with the baddies, you could always get a Unimog and run over them. (h/t Zach Braff).
[Photo: Police Mustang]