Patch v1.06 has been released and it fixes the broken races. This guide is no longer necessary for obtaining platinum.
Original guide below.
Patch v1.05 broke the game and makes the Platinum unobtainable.
However, it's possible to "downgrade" your game to v1.04 and get the trophies with your current save file and without replaying major part of the game. The save file created by v1.05 is still compatible with v1.04.
This is not a game hack or anything like that, you will still need to do those races just like everyone else, except they will load now.
Before you start
Read this guide from start to finish at least once before attempting it.
The procedure is fairly technical and might not be easy to do for everyone. It takes about 30 minutes to do. More if you are doing this with digital download.
I used physical disc. Digital can also be downgraded. I have done only partial testing - see my post below. Further confirmation and full digital downgrade done by CoffeePS.
Instructions for digital version by /r/sdrawkcaBdaeRnaCuoY from reddit. These instructions follow the steps in this guide.
The basic idea is to block v1.05 update and instead make the PS4 download v1.04. Once it finishes the download (it's only 406MB, not crazy 13GB!), disconnect from network, start the game and get those last 2 races done.
For spoofing the request, I used Charles Proxy which acts as a MITM and allows overriding URLs in HTTP requests. Go ahead and install it, it's free for 30 days.
Start Charles on your computer. Write down your computers local IP address. It will be something like "192.168.0.5" or similar.
Go to Proxy settings (little cog wheel) and enable transparent proxy:
Go to your PS4 network settings and setup network. Either Wi-Fi or Wired works. Choose "Custom", set everything to default until you reach "Proxy" settings.
Set the IP from step 2 and in the port field, type "8888" (default port for Charles unless you changed it).
Test your connection in PS4, it should work and also the requests should start appearing in Charles app window.
Insert Mad Max physical disc, it should start downloading v1.05 patch right away.
Watch closely requests in Charles window, one of them will be to:
This is "CUSA00054" - EU version
... or ...
This is "CUSA00103" - US version
This JSON file contains description of the update and tells PS4 where the actual patch files are.
You will need to map this request from v1.05 JSON to v1.04 JSON. Right click on the request, choose "Map Remote..."
Full URLs are:
The window looks like this:
"Map From" will be prefilled with v1.05 (A0105) patch URL:
You will need to fill "Map To" values with v1.04 (A0104) patch URL:
... or ...
Go back to your PS4, stop the download, delete the game and reinsert your MM physical disc.
It will once again start downloading patches but this time it will download v1.04 - it should be 406MB and should only take couple minutes to download. Your PS4 will be confused and say it just downloaded v1.05, this is OK.
Once the download is done, it might start downloading actual v1.05. Make sure to block that patch. Personally, I closed Charles app as well as disconnected from internet via PS4 settings.
Start the game, it should verify your PS4 save file just fine. Once you try to load your save file, it might be still installing from the disc so let that finish as well.
Get your last couple races done and celebrate your new shiny platinum.
You can manage your remote mappings via Tools > Map Remote (Ctrl + Alt + M / Cmd + Alt + M) (thx @Sergen)
It's possible to setup remote mapping before you insert the disc for the very first time and this will save you about 5 minutes. I'd only recommend this for advanced users who have done this before.