Kalamazoo-Reynolds has taken over rival MMI Automotive, developer of the Automate dealer management system.
The acquisition of the Swindon-based IT business comes just over a year after the company completed the £21.7m purchase of DCS Group, another rival provider of dealer services and software.
Reynolds and Reynolds, parent of Kalamazoo-Reynolds, then told AM it wanted to build a 30-35% share of the DMS market in Europe.
In 2003 it also bought German DMS provider Incadea.
MMI Automotive was founded in 2001 by managing director David Hayward, from a management buyout of the Automotive Systems division of Lynx Group.