Hi Rob,
Nice to see a new project!
Love the design, few things I would consider though...
1. The social media icons are hyperlinks but the text isn't and I immediately scrolled over that instead. Perhaps make both hyperlinks to increase clicks.
2. If you're doing a soft launch you might want to consider a free offer with count down to populate your database.
3. Relating to point 2, as you're a new site you might want something that says "XXXX happy customers and counting" linking to how many cars are listed.
4. The arrows explaining how the process works is simple but you may want to number them so people following it easier. Even make it stand out more.
5. On pages like "How it works", once I've read to the end and want to list my car I need to redirect myself back to the homepage. Stick a big button "Get listed now" that takes me there, it might increase conversion rates.
6. To inspire trust you may want to link out to review sites. I did this with one site and noticed it definately helps gain trust. People want to see what others say away from what you have control over.
7. The guarantee is good but not bold enough. Smash it in their faces that this is an unbelievable offer.
Hope this helps.