A number of new and exciting automotive trends are emerging these days. Among them is the extensive adaptation of touch screens and voice commands inside, as well as more “fluid” design language and of course bigger and bigger wheels. Another trend that is making waves is glass roofs, which are already available on a number of luxury cars, as well as performance cars like the Ford Mustang.

It may surprise you, but this is not a new trend. Rather, the origins of transparent roof date back to the 1954 Mercury Sun Valley, a car which featured not a glass roof, but rather a new-fangled transparent material called Plexiglass. The Jalopy Journal has a nice nostalgic look at this neat car.

There was also a Ford version, called the Crestline Skyliner, though the Sun Valley is the more desirable and better known of the two. It’s primary selling point was a Plexiglass half-roof that allowed drivers and passengers to peer out into the sky. The Plexiglass was tinted to keep the sun and glare from blinding the driver.

It was America’s first transparent roof car, and that old trend is starting to make a big comeback. Ford has offered a glass-roof option on the Mustang for a few years now. The new Lincoln MKZ will also offer a full-glass roof, though both cars owe it to the Mercury Sun Valley, the first car to offer a see-through roof.

Funny how all trends seem to come and go, only to return once more…