if you "know" something to be true you must be certain else, there is a probability of it being false.
regarding your example of the parked car, you don't know it is located at a particular spot, you have a recollection of where it is located.
secondly i believe that when you use your senses , no knowledge can be derived from it.
all knowledge is abstract.
for example, as silly as it sounds, you can say , i know i own a levenson amp, but you can't prove it using mathematics or logic, since it requires you to see the amp.
yes this approach is radical skepticism, but it is my concept.