You and your daughter were alone, and your first priority is to her. Even if the guy was genuine I don't think you did anything unreasonable. This is the second story here about people being stopped for help with "car trouble." Is this a common thing? I don't live in the US and I don't drive so I don't really know what it's like, but is this what you do when you have car trouble? Just ask random strangers for help?
if you have skillz and money, you call AAA or google "roadside service." Here's the trick: we're empathetic to trouble, we've all been there and into this chasm parachutes the con artist. Think about it: If you have any sort of social net, you call your social net. If you have no sort of social net, you rely on paid services. If you have no social net and no ability to rely on paid services, you're staring into the abyss of homelessness. And nobody wants to be the person who pushes another human being (or beings) into the abyss of homelessness, so we try and help. And we lose money and sometimes worse.
It's amazing how some things work. Every Saturday I take my daughter to dance class in downtown Durham. There's a coffee shop below the dance studio. I normally sit there and work. Today, a man approached me and asked me if I could buy him a coffee and a cookie. I gladly did. His name was Tony, we talked about the weather, it's a beautiful fall day here. Sunny and about 50 degrees out. Tony was worried because winter is around the corner. It was a pleasant exchange and I was glad to help. He approached it in a legit way. Everyone should be able to have a cup of coffee. I now feel someone exonerated. Edit: I'm still sitting here in the coffee shop. Some others in here saw him ask me and saw me buy him the coffee. A woman have him a couple of dollars and another couple bought him a gift rad for the coffee shop. -Tony is cleaning up today!
When owning a car, there are certain things that will just occur. For example, you will get a flat tire, your battery will die etc. These are things that it is not uncommon to ask a stranger for help with. Why? Because all it takes is a bit of sweat and no money to accomplish. Strangers have jumper cables, strangers may be better at changing a tire. However, asking a stranger for money to fix your car is not common.