Advise a good company that can make a great quality marketplace on the automotive theme

Developing a marketplace is a serious business. It should only be trusted to professionals, because it's hard to compete with marketplaces. You can contact this company https://www.codica.com/blog/how-much-does-it-cost-to-build-marketplace-website/. There is a description of everything that involves such development and how much it all costs. This is the thing which really should be given serious attention. The number of clients depends on the quality of the site.

Looked at the portfolio of the development company that you posted and thought about rebranding and redesigning the site. I haven't had a website updated in a long time, and it was made about six years ago. Having a good, attractive website is very important.