TYNGSBOROUGH — Marybeth Shanahan, owner of the Dream Diner, waits on tables and greets customers. And on Saturdays between May and September, she hosts an event straight out of the carhop era.  The diner doesn’t pretend to compete with the restaurant chain Sonic or smaller carhop establishments that dot the New England landscape. It’s understood that the Saturday event, advertised on the marquee, is a classic-car show.  But the five waitresses who show up for work wearing crisp uniforms are a throwback to the days when carhops raced outside to claim their customers and the fleetest earned the best tips.  Patrons who pull into the parking lot in spotless Chevys or antique Fords could easily imagine a server running to take an order.  But the Dream Diner offers the experience without crumbs on the seat or a sticky door handle. “These cars are so nice they don’t want to eat in them,” Shanahan said. “No one wants to dirty their car.”  Customers, no matter what they drive, can be served in their cars at the Dream Diner’s weekly event. But nearly all eat indoors or outside on nearby picnic tables.  Customers can be served in their cars at the Dream Diner’s weekly event. But nearly all eat indoors or outside on nearby picnic tables.  On carhop Saturday, the diner opens at 7 a.m., two hours before the antique cars begin crawling into reserved spaces and a father-and-son deejay team cranks up the tunes. Inside, the booths and counter seats begin to fill, and a waiting line forms a little past 9.  Shanahan, who grew up in Lowell and Dracut, was 26 years old and working as a general contractor in 1997 when she heard that a former doughnut shop on Middlesex Road was for sale. She bought it, gutted it, and restored it to resemble an old-fashioned diner.  Marybeth Shanahan bought the former doughnut shop on Middlesex Road, gutted it, and restored it to resemble an old-fasioned diner.  Shanahan had grown up in her aunts’ Four Sisters Owl Diner in Lowell, launched in the early 1980s and still owned by one of the aunts. She was waiting on customers by the age of 7. By the time she was 18, she’d saved enough from her jobs to buy a new BMW in cash.  “There’s nothing you can’t do,” her mother, Bridget Trepsas, used to tell her.  Now, Shanahan and her husband, Pat, who helps out on the weekends, are teaching those lessons to their daughters, Mya, 10, and Molly, 9 — miniatures of their mother in pink waitress uniforms.  In the parking lot, Norris Noyes, 79, a retired heavy equipment mechanic from Burlington, arrived in his 1965 Ford Thunderbird convertible. There wasn’t a speck of dirt on his shiny car, but Noyes said he wouldn’t mind eating at the wheel.  If her customers asked, Shanahan said, she would happily oblige. But judging from the full house, she concluded that people can enjoy a Saturday carhop without the car service.  It’s understood that the Saturday event, advertised on the marquee, is a classic-car show.
On summer Saturdays, the Dream Diner in Tyngsboro brings back the look and feel of an old car hop. But the event, advertised on a marquee outside, is really a classic car show.