There were no incumbents on the business.
The agencies will be tasked with relaunching the brand, with Karmarama creating its first TV ad.
The campaign will also feature digital and social media activity.
James Wilkinson, the founder of Zuto, said: "We are thrilled to appoint Karmarama and PHD as we undergo the transformation of our business and have huge ambitions to build Zuto into a household name."
Car Loan 4U launched in 2006. The rebrand follows an expansion of the services offered by the company.