Online car marketplace, thoughts and suggestions!

Hi guys, I'm working on an idea for Startup Weekend and it's about cars. It's an app where you can buy and sell cars along with social and fintech (auto loans, BNPL and more) features I wanted to get your thoughts, feelings and some suggestions about it.

I was also wondering if say a EV rental platform or say corporate car lease/purchase marketplace would be a more solid idea than this? I'd love to hear your thoughts.

Note to admin: No, I will not promote.