Translation:Access by car is not possible.
The dictionary hints say "eine Anfahrt" is a journey--not quite the same thing as access. The English sentence says I can't get in there (into a particular place) with a car--for example, there are no roads, or cars are not permitted.
Saying a journey with a car isn't possible means something broader--I can't drive, or the roads are generally unnavigable.
Which translation is more accurate? Am I missing something here?