Doing a quick web search - there are quite a few copycat stories. Never any mention of how his car got stuck, nor whether he'd tried to reach safety or call for help, nor a missing person police report, nor any search for him, nor ...
Not saying I think highly of the Daily Mail - https://www.dailymail.co.uk/news/article-2103339/Swedish-man... - but their backstory (the man being deeply in debt, depressed, estranged from his family, and recently broken up with his girlfriend) would seem to answer a lot of questions.
Isn't it just possible he got stuck in the snow?
Based on the pictures of the car, I can't even imagine how you'd get the car stuck there, much less get stuck inside the car.
This was a rural area, but he was a few hundred meters from a big road. Surely he could have just exited the car and walked there.
If someone were significantly overweight, they might be able to survive 2-4 months without significant caloric intake.
The problem is numerous risks: neurological, cardiovascular, gall stones, osteoporosis, kidney and liver concerns. These are better than dying, sure, but it would be better to avoid tempting fate and permanent injury in the first place.