Usually,I promote a new website thru blogs so you can interact with your customers or potential customers. I always name the blog the same as my domain.It seems to give more importance in the search engines.Posting information about the company or product.
Try google adwords...focused to your targeted sites...probably like travelling sites or bus ticket hiring etc....
You should work on two strategies, both long term and short term. Short term is to get as many traffic to your sites a possible. Which many members had already mention like article marketing, social networking (Facebook,etc) Long term should get your site rank well in serp. Start building a good amount of decent backlinks and continue to increase your content.
THANK YOU EVERYONE FOR BEING SO HELPFUL! Our numbers are really increasng! Keep the thoughts on the website coming in as well. Oli
Pretty nice idea. I think if you can get more people to submit their stories of using goCarShare, then it might be more convincing. Good luck.