OneSwoop went live this month with £31m backing from bluechip firms like HSBC, Andersen Consulting and Marks & Spencer.
FiredUp enables consumers to bid online for a range of goods and services, including used cars from Vauxhall's Network Q operation. Business development director Robert Avery expected more manufacturers and dealers groups to sign in the next few months.
Newcomer Carstorm.com entered the fray this week, claiming to have signed more than 8,000 dealers across the EU. Dealers will compete online to provide the best quote on a chosen new car.
Carstorm has been launched in association with the AA, which will provide online financing, insurance and extended warranties.
OneSwoop boss Mr van de Ven said dealers would not be driven out of business despite his intention to “put customers in the driving seat.”
He deflected criticism over support by Government e-commerce minister Patricia Hewitt, who spoke at the launch, denying any knowledge of her previous connections with OneSwoop backer Andersen Consulting. Ms Hewitt defended her actions, claiming it was right for the Government to back “another step forward in the growth of the internet”.