"Reasonable suspicion of a crime" is an objective legal standard that doesn't mean the same thing as "they look suspicious" or the situation itself is "suspicious" -- it means that the officer thinks that a specific articulable crime has, is, or is about to occur. They don't have to be 100% sure, and they don't even have to be correct about what the law even is, but they do have to believe a law was broken.
Being unusual by itself does not legally qualify for reasonable suspicion of a crime or infraction, because being unusual isn't a crime.
Now, the officer could be interested in the car because it is a banana, and want to stop it to take a picture of it, but they have to have suspicion of some specific violation first.
https://en.wikipedia.org/wiki/Whren_v._United_States
For example:
1. "Hey that banana car looks weird" > "it doesn't look like it has turn signals" > [pulls them over] > "hey do you have turn signals", "yes", "ok my bad have a nice day" = legal, because not having turn signals is an equipment violation.
2. "Hey that banana car looks weird" > [pulls them over] > "hey is this thing legal?" = illegal, because looking weird is not a crime
A cop sees what is clearly a hand-made banana car driving past them in the other direction on the road. What do you feel like are the appropriate actions for that cop to take in those circumstances, with just the facts available to them at hand?
I’m not arguing that the cops we have do not regularly and aggressively abuse their power and violate the social contract, but I’m struggling to see how we would want a cop to behave in an ideal world in this circumstance that isn’t “pull over the banana car and make sure it’s safe.” From the sound of it, they’re not ticketing the banana car, they obviously haven’t impounded it, and knock wood, they haven’t shot the driver yet, but what would your expectation be for them in that situation?