Dominion

In the distopian near future, air pollution has become so bad that going outside can be fatal to your health and crime is so great a problem that the police have tank units - such as the Newport Tank Police who patrol the area "between the Setouchi Canal and Osaka Bay". Despite being a Japanese police unit, the Tank Police features officers from around the world and is devoted to crushing crime (literally) with brute force. The central character is Leona Ozaki, a young woman who, along with her lovestruck partner Al Cu Ad Solte, operates a mini-tank named Bonaparte. Bonaparte's a laughing stock amongst the other Tank Police due to its small size but Leona is utterly obsessed with it. Along with dealing with everyday crime (and the complaints and paperwork that result from conducting tank operations in a crowded city), the major occupation of the Tank Police is tackling the elusive criminal mastermind Buaku along with his catgirl sidekicks the Puma twins and the rest of his gang.

Source: Anime News Network Encyclopedia