Your dog has already been hit by a car. You cannot let her off lead in an unfenced area until you have a good solid bond created by lots of training -- that is you training, not whoever had her before you.
Next, you need to learn how to train and command your dog. If you have not trained your dog to come, then you have no business giving that command, in German or English. Since someone did give her some training, it should be easier for you to train her into the commands. But there is more to it than using the word. For one thing, do not give that command unless you can enforce it, immiately.
Here's what you do. Reach in your pocket and get a delicious tid bit, piece of gooey hot dog, and don't say, COME. Call her name, if she comes, give her the treat. Good Girl! She needs to know that coming to you is a good thing. NEVER, EVER call her to you to berate her or punish her, because all you will do is punish for coming. That will teach her not to come to you.
Now, when she is coming, good, using just the name, add in your praise for coming, Good Come. Good Girl. Now, when you go about training the COME command, you need to have a line her. Just start when you are walking her, back up and call her, COME, She turns and comes, Good Girl, add a SIT, and make sure that she sits close enough for you to take the collar. Treat when she sits. When she comes very well from short distances, slowly increase the distance, and eventually, you will be phasing out the treats. ALWAYS praise. Praise is free, you can ramp it up, or give light praise if you need her to maintain an even keel. But once she is doing very well from a good distance (long line). Then you can start treating only ever third come, or only for the best sit front, or only for the quickest comes.
It is called training. Even if the dog has been trained previously, they have to be trained to your style, you have to get repoir with the dog. The dog needs to understand that she needs to do what you say. And if you give her commands that you cannot immediately reinforce, you are training her to blow you off.
Jenna, RN CGC & Babs, CD RA CGC HIC
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