The 'business wins' were achieved in three months since COVID-19 restrictions were lifted in the UK, RTC said.
The digitalisation company said the growth signifies that dealer confidence remains high when it comes to investing in digital solutions.
Richard Robinson, RTC’s chief operating officer, said: “The appetite for digitalisation during the UK’s various lockdowns was huge, but it was matched by the enthusiasm motorists showed for an in-person experience once showrooms were allowed to reopen.
“That necessitates a hybrid approach, where online and physical approaches to retail and aftersales are managed together as part of a coherent whole.
“As the automotive market continues to adjust to its post-lockdown environment, we’re seeing the formation of a new generation of dealer operations: joined-up, digitally managed and future-proofed.”
Mark Busby, commercial director at Hendy Group, said the group sees digitalisation as "essential to give its customers a positive experience that fulfils their diverse needs".
He added: "I am pleased to say that RTC is making it as easy as possible for us to implement this group-wide, configuring its solutions to our specific goals and handling the ‘heavy lifting’ so we can concentrate on securing business wins.”
Scott Stenning, director of Arbury Group, said: “Our group has grown over the last 20 years, and we had a requirement for an aftersales software solution with suitable power and a high level of customisability to enable us to maximise our aftersales opportunity.
"RTC was able to deliver all of this, and we are looking forward to completing the onboarding and fully realising the benefits of its digital tools.”
Karen Parker, head of aftersales at Heritage Automotive, said: "We have enjoyed a long-standing, beneficial relationship with RTC, driven primarily by a focus on improving the customer experience.
"This has held true as our franchised network expanded, and as priorities changed rapidly during 2020."