I have the same issue. Tried lowering the settings, didn’t help. Sent you guys an e-mail with the benchmark. Here’s the spot where it happens: Forza Horizon 4 2018 09 13 09 18 55 01 - YouTube
After you are done with the places that the problem persists, you can go back to your usual resolution as I have done so.
Using a lower resolution may also make the game work harder on having to render the incoming roads, which prompted me to use rewind to wait until they were loaded in properly.
I had a lot of random CTDs and never been able to go pass the last jump at the end of spring…
I have an external USB soundcard and I disconnected it and used the nvidia HDMI audio to my monitor. I have NO MORE CTDs!
Seems there’s a lot of problems related to audio in the demo. I had no audio problem but the CTDs were directly related.
edit: Just to mention that the overall performance I get are much better than in FH3 so that’s really good news!
Last thing: Any hope for an HDR patch for FH 3 someday?
Ok so I did notice some audio problems glitching and cutting out I use the Plansonic RIG 800 So will unplug My sound 
And see what happens.
Ok so got the sound working but still crashing have up loaded video to U tube
PC specks are
Intel® NUC
Intel Core i7-8809G 3.1GHz (up to 4.2GHz Turbo)
2x 16GB DDR4 2400+ SODIMMs
Radeon RX Vega M GH 1063-1190MHz GPU, 800MHz Memory 4GB
512 GB M.2 SATA SSD Operating System and Apps
1TB M.2 SATA SSD Game’s only Windows and Steam
4 TB External Hard drive USB-C for Photos and Back up files
Integrated Wifi Intel® Wireless-AC 8265 + Bluetooth 4.2
OK so a UP Date I got a hold of Intel and they Linked me to a Beta Driver for my Video Card and this has worked as I found the Crash was being caused by a massive memory leak in to the Shared Video memory the Entire 16GB was filling up to 100% in about 1 minuets or less The Beta Drivers have Fixed this Problem on my system and game is running nicely
Using Avira A//V and couldn’t get past Spring due to crash to desktop, although not always right at the end of spring. Excluded the drive the demo is installed on (SSD, only has this and Horizon 3 on it) and no more crashes.
Could probably just exclude the WindowsApps folder and WpSystem folder instead of an entire drive as that’s where the Forza files live.
My first play through, I got loads of times where my car physically slowed down randomly in the snow. Second time through that didn’t happen at all in the snow, but in Autumn I did get a random point where the map slowed down in loading in, and then just hit the brakes on my car to about 20mph. Very not cool.
My first play through, it crashed at the end of Summer, just when it tried to load the cutscene. But it was a proper crash, grey screen, mouse cursor could be moved, but ctrl/alt/del did nothing, alt/tab nothing, alt/F4 nothing, had to push the reset button on my PC.
Second playthrough it CTD end of spring as OP said. Can’t get benchmark, no anti virus.
I’ll give it one more go, but I gotta say, even though it’s a demo, it’s really dampened my excitement for this game
Go in to Settings Difficulty and turn of assisted breaking and TC and Stability control if they is on sounds like you have Auto breaking on
it seems to definitly fix if you keep normal graphics settings but put the resolution onto 720 for the opening section
I’m getting the same problem
I found a fix just now to get past the first race without a crash and it would always crash for me there until now. Reset the app. Go to app settings and select reset to clear its data. Then start the game and continue directly without restarting the game ever. It doesn’t crash for me in that case and you lose progress after a restart anyway so there is no harm in doing a reset.
[Mod Edit - Abbreviated profanity, profanity and profanity that is disguised but still alludes to the words are not permitted - D]