APB: Reloaded's Unreal Engine upgrade is detailed in the latest dev blog at GamersFirst. In it, we get word that progress is slow but steady as the current version (from 2008) needs to be stripped and rebuilt due to the custom-built additions made in the original engine. Think of it like when you have to manually update your mods every time World of Warcraft has a new patch.
Although the latest version of Unreal will aid with performance and compatibility improvements, the Reloaded team says that you may not even notice much of a difference visuals-wise.
GamersFirst hopes to roll the new upgrade out soon, although a release estimate is still to come. Check out the full dev blog for more details on the Unreal Engine upgrade.