It looks like day of the little deuce coup and daddy’s T-bird are over. Baby boomers who loved their sports cars are just too danged old.

Boomer sports car enthusiasts are cruising toward 70 with their peak spending years behind them. Blame arthritic knees for making it too hard to get in and out of those low-to-the-ground beauties, not to mention the impact of a stiff suspension on one’s back.

“Boomers are starting to age out of sports cars,” Eric Noble, president of the CarLab, a consulting firm in Orange, California, told Bloomberg. “When you get into your 60s, comfort becomes more important. Sports cars are not going away, but the market will get smaller.”

Ford Motor Co. idled its Mustang plant for a week following a 9 percent drop in sales compared to last year. In September, Mustang sales were off 32 percent compared with August, allowing the Chevrolet Camaro to overtake it as the best-selling sports car for the month of September. Even the venerable Chevrolet Corvette and Porsche models are seeing a sales slump, Bloomberg reported. Porsche reported an 8 percent drop in passenger car sales while its small SUV was up 30 percent this year.

There aren’t enough Gen-Xers to make up the slack, and millennials just don’t have enough cash. ITech noted younger buyers seem to prefer electric cars, hybrids and small cars to muscle cars.

Ford estimates 40 percent of Mustang buyers in 2016 were baby boomers, down from 50 percent in 2013.

“We are seeing some older boomers move out,” said Mark Schaller, marketing manager for Mustang. “The Mustang is a life-stage vehicle.”

At Chevrolet, Corvette and Camaro sales are down 14 percent and 11 percent, respectively. Todd Christensen, marketing manager for the Camaro and Corvette, told Bloomberg the company is hoping to spur ‘Vette sales with the new Grand Sport, which will be about $14,000 cheaper than the high-performance Z06 model. Chevy also is marketing a smaller Camaro to younger buyers.

Jessica Caldwell of said part of the problem is coupes falling out of favor as lifestyles change. When it comes to Porsche and Mercedes, buyers are opting for sporty SUVs.

“Boomers are coming out of pure sports cars, but they’re not willing to sacrifice pure driving,” Branden Cote, AMG manager for Mercedes-Benz U.S., told Bloomberg. “The idea of a sports SUV was incomprehensible 10 years ago. They’re not giving up spirited driving; they’re going to a different type of sporty driving.”