The 1930s arguably was the most important automotive decade since the advent of the automobile. A lot of interesting developments happened in America during this time: streamlining, multiple-cylinder engines (especially Ford mainstreaming the V-8, plus the advent of V-16 engines), “Turret Top” all-steel bodies, Dubonnet independent front suspension, and hydraulic brakes, among others.

Below we have four 1930s cars currently listed for sale on ClassicCars.com. Can you tell us what they share in common? Post your answer in the Comments section below. While you’re at it, can you tell us the year/make/model of each?

Need a hint? Click on a photo to reveal each car.

You can play this automotive puzzle on The ClassicCars.com Journal every Tuesday, plus another one on Saturdays. To play past car games, click here.