The “Have you really tried to save gas by getting into a car club?” propaganda poster was designed by Harold Von Schmidt in 1944, it was one of a series of posters designed by Von Schmidt during World War 2.
The image depicts a bloodied and bandage soldier staring into the camera. Blood drips from underneath his helmet down onto his chin. During World War 2 there were shortages of resources such as food and gas in the U.S.A. Car clubs were set up to encourage car pooling and to save gas. This image plays on the fact that those who were not working towards saving gas were not supporting soldiers on the frontline.
The main protagonist in the image who is overseas fighting for the liberty of the U.S.A is suffering because of people not car pooling. The effectiveness of this poster is not documented. However, you can imagine it playing a fairly significant part in encouraging people to share cars.