Hey, just wanted to leave my gameplay/mechanics suggestions that I think would be hopefully relatively simple to add. Feel free to leave critique!
Car Flipping
As it is in GTA5 or Halo, where you can shift your car back on its wheels if it has flipped over. I think this would be a really great feature, sometimes there are no pedestrian cars around you and you're far from a car spawner. This could even be a modification for the car itself, where you'd need to have that equipped and take up one of the slots for the car mods. I also think a lot of new players might naturally expect this to happen, as flipping your car happens quite a lot (at least for me, maybe I'm a bad driver )!
Gun/Economy Mechanics
I think it makes sense to have a level up system with the contacts, but I think it deters new players from continuously levelling up since it takes a while to get access to a wide array of actually good guns. Personally, I think it would be better to have the weapon unlocks as well as some mods towards the beginning of the contact progression rather than all throughout, perhaps leaving the more customization oriented stuff at the end of the progression, just to flex that you made it that far. Of course not all weapons have to be at the beginning, but I think it'd help keep players playing since this game is a customization game as much as it is a competitive combat game.
I also think (and this may come with some warranted feedback), that players should have some basic access to guns in each category by default and not have to keep leasing guns. Starting off as a fresh newbie with just the STAR rifle and pistol makes gunplay in different scenarios particularly tricky, especially for a new player. Perhaps having permanent access to a shotgun, sniper and SMG would alleviate this but I'm not fully sure!
Matchmaking & Missions
The missions are fun as hell to play, sometimes certain stages can be annoying, but I think if there were missions in combination with fight club type events (both in the same district i.e., financial or waterfront) it would be super fun. If you're not in a mission, you could always just drive over to wherever the active fight club type event is and do that. Or you can just queue up for a regular mission.
I think also this idea of splitting the districts into different types has had a negative impact on the matchmaking, where a more "transient" approach would be potentially better. Something where, lets say you're in Financial and you're waiting for a mission, if one is found in a different Financial district you could be teleported/connected to that district and put into the mission.
Of course, APB doesn't really have the player base numbers right now to consider implementing that, so I think how it is right now is fine, given the fact that there's simply not enough people playing to begin with. But something to consider nonetheless!
Spawns
The respawn system is, questionable at best. It get's the job done, and car spawns are a very interesting mechanic to sprinkle on top. But I'm not sure if the idea of clicking randomly placed circles is the greatest idea. I'm not really sure either though, what could be better than that. Perhaps bigger circles, where you pick within a radius of selection where you want to spawn. At the end of the day, the [respawn] locations aren't always the greatest, the degree of freedom is lacking, the predictability of where you'll be able to spawn is null and void. I don't know whether a system like Fortnite's "rebooting" where players can respawn other players who had just died would work, or if something else entirely would be fit. I do know the current system is questionable.
Misc. Features
Better Waypoints/Markers: We already have waypoints, but they suck and honestly are annoying to use. Something akin to CS2 where you can effectively "ping" a location (where an enemy might be) as well as other in-game info. This type of thing I would imagine would be simple to implement and make the waypoint system used a lot more I'd bet. Right now you open a map and right click and that sets a waypoint, but you generally only do that when you're dead or if you deliberately stop and open the map for a second. The waypoints are also permanent, which just makes them get in the way of stuff on the screen. Instead, I think it'd be better for them to be a key you can press that traces to the location where you spotted something (i.e., enemy, car, objective, etc) and then fade out after a short duration. They would work similarly by only being shown to teammates.
RTW Shaders Option: Super unnecessary, but god I'd love to see that button that enables it one day.
Anyways, that's all I have. Peace and love.