The police want to search my car and I am sure that there is nothing in it. (They say if I don't allow them to search my car they will get the dogs and it will take a lot longer and I am in a hurry).

I understand you are in a hurry but do not agree to let them search your car. You're never sure of what is in your car unless you are the only one that has entered the car. Someone may have left drugs, guns, or other illegal items in your car without your knowledge. If you agree to let the police search, then they can. If you do not agree it is much more complicated and unlikely that they will be able to search your car legally, though they may search it anyway. Watch them as best as you can. If they do search your car see where they look and how quickly they discover the stuff. Don't answer any questions. If they find something do not claim ownership or deny ownership -- don't say anything. Call me immediately if you are charged with a crime.