Once while on a bus in Charleston, SC, I saw a fancy green car while I was staring out the window. It had the Autobot symbol on the side.
I was amused, and it made me think about things, like what if Transformers were real? Here's the bunnies
1. An Autobot (or Decepticon if you want to make things interesting) keeps running into the same human who somehow manages to never realize the fancy car he/she admires is a sentient alien robot. Eventually, the bot gets so used to seeing the human, that when the human isn't seen for a few days, the bot panics and thinks something has happened to their human.
2. A human who is a total Transformers geek notices a car with an Autobot (or Decepticon) brand. Thinking it's a fellow Transformers nerd, they stick around for a while hoping to make a friend (They don't have a lot.). The catch is that Transformers are real, and this car is one of them. The bot tries to get away using a holomatter avatar (or something similar), but unintentionally agrees to meet up with the well-meaning geek later on. Now the bot has to figure out how to distance themselves from the human (so they won't get killed) without hurting any feelings.
3. A human stumbles upon Transformers fighting. That's the plot of most of the shows, but the catch is that the Transformers are a franchise in this universe. To make matters worse, the human keeps stumbling across the fights (Which would be quite amusing if they took place all over Earth), and he/she can't figure out a way to explain this without looking crazy.
4. Along with the Autobots and Decepticons, several neutral civilians arrived. They have no weapons or training that would make them decent soldiers. So instead, they earn a living by doing their old jobs and giving rides to humans. In most cities, you'll find at least one neutral Cybertronian willing to give you a lift if your car breaks down.