Mafia: Definitive Edition

There are a total of 36 vehicles you can own in Mafia. All you need are 15 to unlock this achievement.
You can easily get the achievement for owning 15 cars during the story. During free roam you have a better chance of unlocking all the cars, all you need to do is just sit in them and they will appear in your garage next time you are there.

All Cars - https://www.powerpyx.com/mafia-1-remake-all-vehicles-showcas...
Hidden Cars (5 Cars available after completing the story, I also have a guide published) - Photo Booth Challenges (5 Cars available after completing the story) - https://www.powerpyx.com/mafia-1-remake-all-phone-booth-side...

Listed below are all 36 cars and how to get them.

#1 Bolt Ace - Unlock at beginning of game
#2 Haverley Tomahawk - Unlock during story, also available in free roam
#3 Bolt Pickup - Unlock during story, also available in free roam
#4 Bolt Model B - Unlock during story, also available in free roam
#5 Bolt V8 - Unlock during story, also available in free roam
#6 Bolt Delivery - Unlock during story, also available in free roam
#7 Bolt Ambulance - Spawns in free roam (rare spawn but can spawn anywhere)
#8 Bolt Cooler - Spawns in free roam, most common spawn in Countryside/Works Quarter
#9 Shubert Six - Unlock during story, also available in free roam
#10 Shubert Six Taxi - Unlock during story, also available in free roam
#11 Bolt Mail - Spawns in free roam, I commonly found it in Countryside
#12 Shubert Luxe - Unlock during story, also available in free roam
#13 Shubert Luxe Taxi - Unlock during story, also available in free roam
#14 Houston Coupe - Spawns in free roam in Little Italy/Chinatown
#15 Crazy Horse - Phone Booth Challenge number 1
#16 Bolt Hearse - Spawns in free roam around Countryside (believe I actually got mine during story mode)
#17 Culver Airmaster - Unlock during story, also available in free roam
#18 Waybar Concept - Phone Booth Challenge
#19 Berley 810 - Unlocks after completing Chapter 20
#20 Smith Moray - Phone Booth Challenge
#21 Smith V12 - Unlock during story, also available in free roam
#22 Eckhardt Crusader - Unlock during story, also available in free roam
#23 Falconer Classic - Spawns anywhere in free roam
#24 Lassiter V16 Roadster - Spawns in free roam around Oakwood/Downtown
#25 Lassiter V16 Sedan - Unlock during story, also available in free roam
#26 Celeste Mark 5 - Spawns in free roam around Oakwood/Downtown
#27 Echardt Fletcher - Unlock during story
#28 Mutagen - Phone Booth Challenge
#29 Manta Prototype - Hidden Car
#30 Disorder - Hidden Car
#31 Eckhardt Elte - Spawns in free roam around Oakwood/Downtown
#32 Trautenberg Sport - Hidden Car
#33 Lassiter V16 Appolyon - Hidden Car
#34 Flame Spear - Hidden Car
#35 Brubaker Forte - Phone Booth Challenge
#36 Carozello C Series - Phone Booth Challenge

Sorry for long post but hope that helps everyone!

EDIT: Looking at my garage I have 38 vehicles to unlock.
#37 Smith V12 Chicago - No idea how I unlocked this, sorry.
#38 Shubert Frigate - No idea how I unlocked this, sorry.