1. Buick Super
Location: Used during Traffic cases.
2. Cadillac Series 62 Convertible
Location: Used during Vice cases.
3. Chevrolet Fleetmaster 2dr
Location: Central. Used by Jack Kelso in the Arson cases.
4. Chevrolet Coroner's Van
Location: Parked near many crime scenes.
5. Ford Police Special
Location: First vehicle in the game. The standard Police cruiser.
6. Hudson Commodore
Location: Used during your Arson cases.
7. International Police Wagon
Location: Many of these are locked when you find them. Look for them at police roadblocks. At the crime scene of "Studio Secretary Murder." Also found at the "Bank Job" Street Crime. (credit: SpinelesS)
8. Nash Super 600
Location: Used during Homicide cases.
9. Studebaker Commander
Location: Parked near many crime scenes, but first seen in "The Driver's Seat" parked beside your vehicle at the railroad crime scene in Central. YOU MUST enter the car before investigating or it will be gone when you leave the scene.
Special thanks and credits
Big thanks to BradyGames. Most of this information came from their guide.
Thanks to every one from x360a.org on the forums for other good input.
Again HUGE THANKS to Doobs for his amazing work on the videos.
I really hope this guide helps in someway. I spent more time on it than I thought I would but I really wanted to do it right. Happy Hunting.