The Challengers

From publisher blurb:

Many great things start small. The CHALLENGERS were founded to tackle street crime and protect the underprivileged. As their successes grew, so did their number, and in time the CHALLENGERS had become a team of five dedicated heroes complete with a base of operations, vehicles, and a support team. Although they are entrenched in dark and gritty elements they work vigilantly to avoid being swallowed up in it, to be good examples, and never compromise their values. They may not be the most powerful heroes in the city, nor the most famous, but you can always count on them to stand up when others can't and always do the right thing.