Few images evoke the lazy hazy days of summer more than a convertible driving down the coast. Soon, though, that image may be pure nostalgia.

Sales of convertibles have seen a steep decline, falling by more than 40 percent in the past decade alone. And with new, tougher fuel economy standards, the days of riding with the top down could be numbered.

Jack Nerad of Kelley Blue Book has owned a 1962 convertible Corvette for nearly 40 years. Nerad lives in Orange County, Calif., a seemingly ideal place for a convertible, but his classic car often stays at home.

"You typically don't drive one when you have one, frequently," he says. Nerad says convertibles are typically the second or third car because while fun, they lack practicality.

Most convertibles have cloth tops that could potentially be easier to break into. They tend to be smaller, somewhat less comfortable cars — especially if you're tall — and the rear seats seem more for show than for riding. They can be noisier. Ironically, in warmer, sunny climates it's often more comfortable to ride with the top up and the air conditioning on.

While convertibles appear to be less enticing for consumers, making them is far less rewarding and more difficult for automakers. In the 1960s, the heyday of convertibles, the frame and body of most cars were separate. "It was easy to plop down a convertible body or a station wagon body or a lot of different bodies on that same frame," Nerad says.

Now, cars are made using unibody construction, which means the body and frame are constructed as one piece. That means a company like Toyota can't easily turn an established car like the Camry into a convertible; the automaker has to start from scratch and create an all-new car.

If there is one thing that makes the ragtop less attractive to carmakers, it's fuel economy. Each manufacturer has to raise its overall fuel economy to 54.5 miles per gallon by 2025. Convertibles are often heavier and less fuel efficient than their sedan equivalents. The mechanism that raises and lowers the top has weight.

It seems counterintuitive, Nerad says. "You oftentimes have stiffening of the chassis that replaces the stiffening that a solid roof would provide." That means automakers have to work hard to make cars more fuel efficient. All this leads to a lack of enthusiasm for the drop top among many.

But not all. "Basically, this car is the most unadulterated encapsulation of everything we are," says Rod McLaughlin, a Mazda vehicle line manager, in describing the MX-5 Miata. The company just renintroduced its halo car — a head-turning vehicle that makes buyers pay attention to the Mazda brand even if they don't end up buying the actual car.

Last year, Mazda sold about 5,000 Miatas. Mazda is willing to take the bet. As is General Motors, which is launching a new Buick convertible. And the luxury brands are keeping pace.

McLaughlin says consumer tastes are cyclical. "I don't think the days of the convertible will ever go away. It's cyclical and there's a point where people feel they do need to drive other cars and they do need giant SUVs and there was a point when everyone wanted a station wagon a while ago." There's something so much fun about convertibles, he says, and they're "more than just Point A to Point B transportation. How can that ever go away?"

Copyright 2021 NPR. To see more, visit https://www.npr.org.