A couple of ways I know are tying a tire to a rope and tieng that rope to your waist and running with it, I have done this and it helps explosion tremendously, another way is, start lying on your belly, have someone clap, and after they clap explode up and run for about 15 yards.
Break away from the cops? What kind of fight or fighter are we talking about here that he needs to run away?
they are tons of plyometrics exercises out there do a research on the web and you dont need fancy equipment. Try jumping squats