Addon Vehicle & Police Scanner SFX Pack

This modification largely expands GTA IV audio in 3 areas: Engine sounds, Horns and Police scanner dialogue.
It has an innovative installation method that does not replace entire .dat15 file. Instead, it loads the metadata as its own DLC, meaning it's fully compatible with any mod that replaces sounds.dat15, such as radio downgraders.

Part 1: Engine sounds.
12 brand new vehicle engine sounds have been added, covering everything from tuners, muscle, vans and jalopies. Vanilla game’s vehicle audio variety has some noticeable gaps, e.g. there's no small diesel or rotary equivalent, as well as a shortage of light inline and ricer-esque sounds (while having tons of heavy V6/8-like sounds). This mod addresses these flaws - you no longer have to frankenstein the FLA configs to achieve something vaguely sounding with what IV has to offer. Now you can assign new, accurate sounds. Most of the samples are sourced from Midnight Club LA and NFS Carbon.

Part 2: Horns.
Modification includes 28 new horn sounds. Most of them are ports from my Vehicle Horn Overhaul mod for GTA V, a few of them were made by Jeansowaty.

Part 3: Police Scanner.
Push your immersion to the max with 201 new police scanner audio lines, including 25 new manufacturer sounds, 27 new vehicle categories and 149 new car model callouts. Nearly every single lore-friendly mod has been covered. 
If you always wanted the dispatch to properly describe your addon car, this is for you. Your vehicles could've never been more seamlessly integrated within the game's world. Huge thanks to Jeansowaty for voicing the dispatcher.

More info can be found in the readme files.