It is new and innovative: “nobody is doing this! We have no competitors!”
Well yeah. Very hard to argue with that.
Unfortunately being all new and innovative and having no competitors isn’t necessarily a guarantee for success. In fact, if nobody it doing it chances are it is probably a good indication that your idea sucks.
But even if the idea is not all that bad and you manage to sell quite a few cars with polka dot prints (“we don’t have to stop at pink and yellow! The possibilities are endless!! This is so scalable!!!”) how hard would it be for people already selling cars to simply start doing the same?
A new and differentiating paint job is just not enough to compete with car makers with hundreds of years of experience.
The same applies to any start-up of course. Don’t just find out if your idea is new, but also how hard it would be for other people to enter your business.
One tip: if you need an NDA to protect your idea that simply means it is very easy to steal. Not a good sign.