Trucks are noisy as fuck anyway.
It's a bit obnoxious how 100+ zombies can spawn immediately after you kill a horde.
Last character had 1200 kills, 1/3 of them wildlife in the streets, because zombies would always spawn directly north of my Garage, multiple times a day. I decided to just suicide because it wasn't fun anymore to kill hundreds of zombies at a time because the game decides to toss them right on top of you. After you get done slaughtering every person that could have possibly lived in the area.
Break a couple windows in a house and come back a week later, you'll find the sills are stuffed full of corpses [Usually Squirrels].
Spawn rates should be directly tied to the terrain and amount of housing nearby. Plains 5+ map tiles from any type of housing or store should not be able to spawn a damn horde for no reason. The zombies would not wander into the plains to find brains. They'd stay in town or in the streets. So there's an in-game reason and a programming reason to do this.
It's just a bit bad when you, as the player, begin to say "Really,
another horde? Didn't I just kill hundreds of zombies a block south of here? While making enough noise to attract all Zombies in the county?" [Which I've done multiple times in a row, just to find a new horde a block away] instead of "Oh damn! A horde of Zombies!"
Or make it so hordes consist of actual zombies [and their limb-variants], with the Ripped-off-from-Left-4-Dead mutated types being made extremely rare, with the exception of the fast ones. The majority of your enemies should not be 'special' zombies. I walked into a hospital and every single enemy inside were Boomers.
It'd give atleast some progression to the hordes as opposed to you immediately getting thrown against spitters, brutes, shockers and necromancers.
Maybe make it so slaughtering them by the hundreds atleast takes a couple hours off the spawn ticker. Something. The spawn system is broken and [as stated by many players] at the whim of the RNG.
Note: I don't mention the animal spawns because it's apparent those are broken. Hundreds of squirrels and bears around you in the streets by day 3 is a big indicator of that.