If you're wondering How to Upgrade Cars at Hao's Special Works but still playing on PS4, then it's worth noting that these upgrades are exclusive to the new-gen versions of the game. This is because the PS5 has a much faster SSD than the PS4 which makes streaming in the game world quicker, and thus allowing for the blistering speeds these upgrades enable. You'll need to upgrade to the PS5 version if you want to add Hao's Special Works tuning upgrades to your fleet, and you can find out How to Transfer Your Character from PS4 to PS5 through the link.