Legality =/= morality
Which one are you trying to argue here? If legality, then don't bring morality into it. If legality, don't bring morality into it.
Since you're stating laws, let's go with legality for now. Let's assume this is America. You say 3rd degree. I'm assuming you are calling it recklessness as no other category you stated really fits.
I'll say it again and go over the evidence in no vague terms:
1) the man in the car attempted to move the guy who was laying in front of his car in thebmoddle of the road (a road which is commonly known for cars to be driving on and in fact not a bed for people to sleep on), out of the way of his vehicle (not a reckless act but the exact opposite).
2) When the guy snuck in front again without the driver noticing, the driver immedietally stopped the car as soon as he realized the man was there again after he attempted a peaceful solution (again, not reckless and shows the opposite intent)
3) The driver then gets out to check where the people are and their distance from his car (again, the opposite of a reckless act as he is planning how to solve the situation without harm)
4) And finally he turns the wheel to go AROUND the guy so as NOT to run him over (again, not reckless and in fact a willful attempt to be careful in extracting himself from a dangerous situation)
All of this done while a group of people have hands on his car, banging on his property, and attempting to vandalize it.
Legally this leans more towards self defense.