Afraid of cars?

Everything scared kabota at first- cars passing, doorbells, traffic lights, etc. you could try what i did: when a car goes by, give her a great treat, like a piece of hot dog. Eventually, she'll associate cars passing with nummy treats instead of scary.

What Amaryllis said. Just feed feed feed.... a frightened dog should not accept food so you won't be "nourishing" fearful state of mind. Make sure you feed her in a playful manner by going backwards with her in front of you, call her name before every treat. Use real smelly stuff, not regular kibble or biscuits. In few days you'll have her ignore cars altogether.

I have been working with a 4 year old GSD for most of his life (He is my brother's dog). I am analytical and take a root cause or cure approach to problem solving so I do not use symptomatic things like treats. Not being mean or harsh here, just saying how I approach these things.

Any who the GSD, Alexander, was also afraid. So I directly embraced his fear, but when he would cower, I had him sit and used my hands to make eye contact them simply give a deep, confident, "you are fine". Then would proceed with walking. And I repreated this every 30 feet or so, and it stopped.

If you are calm and confident person, your dog will respond in kind.

Is there somewhere you can walk her where she's not as close to the cars going by, like a park for example? If so, start there, work away from the traffic with lots of rewards, and gradually work closer to the road each time till she's happy about the whole thing. Make it a fun thing, also expose her to new things that are positive beside the cars, so she's associating new things with being fun.