Your car is permitted on the property owner's property pursuant your abiding by his rules of access, and not carrying a gun on to his property.
The moment that you cross his property line carrying a gun IN YOUR CAR, you are in violation of his rules of access, and you can be forcibly removed.
Don't believe me?
Stop a cop anywhere and ask them.
By the way your pants and your socks and your underwear are your property as well...do you believe that you can stash a gun in your pants, your socks, or your underwear and enter a property where guns are not allowed?
Ask a cop.
Luis, althought I agree with you, I should point out that asking the police (or a prosecutor) for a legal opinion is a very bad idea. First off, the police are under no obligation whatsoever to be honest. Second, their understanding of the details of the law is oftentimes somewhat vague.
The best thing to do is to ask a private attorney after paying a retainer fee - that way, at least you can sue them for malpractice after putting their advice into practice blows up in your face.