The Planning Board on April 10 will open a public hearing into a plan by Group 1 Automotive to expand its auto dealership campus on Route 114 near Interstate 95. The Texas-based company, which owns Ira Automotive Group, has applied for site plan approval for the project, according to Kate Day, the town’s senior planner. Group 1 Automotive currently operates several dealerships at 97, 99, and 99R Andover St., and has acquired the adjoining 101 Andover St. site formerly occupied by Jimmy’s Allenhurst restaurant, the company said in its application. Group 1’s proposed site plan would combine its existing and new properties into an overall 19.4-acre dealership campus. The proposal calls for constructing a 9,000-square-foot building on the former restaurant site to be used for the sale of used Toyotas. It also proposes building two additions to an exiting Lexus building: a 6,285-square-foot service area, and a 25,360-square-foot, single-story Toyota sales and service area. The existing Mazda dealership and former Audi/auto insurance building would be demolished, while the existing Porsche and Subaru dealerships would remain. Under the plan, the traffic signal at Brooksby Village Drive would become the main entrance and exit to the dealership campus.