Really sad right now. All my save games got deleted out of nowhere and I will have to start all over. Losing all my cars, designs, credits, gift cars with the special designes… Maan, all that time spent playing… gone. 
It’s tempting to sell the whole Xbox as Forza was the only game I played.
I lost mine 2 days ago. Level 202, almost all of the career complete. I had about $15 000 000 too. For me I was starting the game, just after the title screen, where you press A, the game hitched and then it went back to the title screen, since then it is as though I have never played the game. All the cars, money, designs and 80 hour all gone! You can look at my achievements… Turn 10 please help! 
That’s exactly what happened to me to! The game froze and I had to reboot, then all my saves were gone.
Tho I didn’t have as much stuff as you I still lost a butt load of cars, around 4.000.000 credits. and my designs… Sad.
This happened to quite a lot of people since the release. Sadly, no one recieved any help.
The only option is starting all over again
Time to launch a class action against Turn10 & Microsoft.
The frequency of these failures is increasing now - and many of us have paid cash for various features that are not able to be replaced by restarting the game.
In other words, Turn10 has failed to deliver the goods as paid for.
The least Turn10 needs to do is allow folks who have lost their games to be made whole by replacing lost tokens.
I will be contacting an attorney on Monday and keep everyone posted.
Good luck with that. I assume you have already contacted support and exhausted your options there? The one time in the past I had serious issues with XBL, support gave me free XBL points for my troubles. I would be very surprised if an issue with XBL actually cost you money and MS did not at least attempt to make you whole.
Are your shared tunes and designs still there?
But the stuff I’d really care about keeping are my shared tunes (typically 2 hrs each) and shared paints (1-3 hrs each). I’m a bit player compared to our big community guys, but it still means a lot to me being “out there” with a few dozen well-crafted contributions of my own. I’ve got scores of unshared tunes and paints, but they’re not the ones I’ve polished to the point of sharing. It’s the shared stuff I’d really want to get back. And I expect that would all still be there.
Either way, it’s gotta hurt for you to lose so much progress. I’ve got 270 cars in the garage and 11M cr in the bank, and it’s been a blast to build it all up and race every car. If I lost it all, I’d be really upset, and would probably ask T10 for 50M credits as a head start on rebuilding the garage. Losing the level would be fine with me: once I got past level 700, I found people in lobbies started dropping out without even trying - little did they know, on all but 1 track I’ve got the racing skills of your typical level-20 driver, they’d have enjoyed a competitive race.
i had to do factory reset 5 profiles with save file for each not loading game data or syncing 2 of them was fine after but 3 made me start new game after doing the 1st races all my cars was in garage i still had my tokens tunes and paint but money was gone and i have to do all races again but its better than not having my cars and tunes