Fresh off its acquisition of Miller Cadillac in Mount Pleasant, Baker Motor Co. has expanded again.

The luxury car dealership founded by Tommy Baker nearly a quarter century ago now owns the former Sentry Buick GMC dealership on Savannah Highway, a hallmark for car dealer Harold Arnold for more than 25 years.

The long-rumored deal closed Tuesday for undisclosed terms, and overnight Baker moved his recently acquired Cadillac dealership from Mount Pleasant to the former Sentry site on the “auto mile” in West Ashley. It is now called Baker Buick GMC Cadillac.

“Combining the Buick, GMC and Cadillac franchises together make a powerful combination,” Baker said Wednesday. “Having three out of the four GM franchises under one roof is a great opportunity for Baker Motor Co.”

Baker owns a stable of luxury cars and called Buick “a neo-luxury” brand and GMC the luxury end of General Motors’ lineup of trucks and sport utility vehicles.

“Their client is entirely different from Chevrolet,” Baker said. “From our market research, we like the buyer and their profile. We think in the future of the automobile business, with the resurgence of GM, this product fits right in.”

Baker’s buyout of Sentry includes six acres and a 63,000-square-foot building on Savannah Highway. He said he plans to build 10,000 square feet of new showroom space in front of the current building, starting in about two months.

Construction should be completed by December. Buick and GMC products will be featured in one new showroom and Cadillac in another.

“Our goal is to have the most impressive GM facility in this marketplace,” Baker said.

Baker also plans to start work immediately on adding an automatic car wash, Saturday service department hours and drop off/pick up and delivery services for all Buick, GMC and Cadillac customers.

Cadillac sales manager Sumter de Brux Jr., whose mother Clydie de Brux and other family members own the former Miller Cadillac site in Mount Pleasant, said there are no immediate plans for the vacated property near Johnnie Dodds Boulevard and the south end of Mathis Ferry Road.

He said the Cadillac move to West Ashley beside Buick and GMC products should translate into an uptick in sales.

“For people shopping along Savannah Highway on the auto mile, it will give us more opportunity if they are looking at Buick and then decide to look at a Cadillac too,” de Brux said.

Baker, who started as a car salesman in 1970 and formed his own company in 1988, bought Miller Cadillac in November. He didn’t rule out further expansions.

“We are in an acquisition mode, always looking for an opportunity to grow here in Charleston,” he said.

Bill Gironda, vice president of Baker Motor, will oversee short- and long-term planning as well as daily operations of the new dealership. Eric Gustafson, Baker Cadillac’s general manager, has been named general manager of Baker Buick GMC Cadillac.

Arnold could not be reached for comment.

Reach Warren L. Wise at 937-5524 or twitter.com/warrenlancewise.