1940s gas bag vehicle modified to deal with deal with gasoline shortages during WWII. The vehicles consume coal gas.
Fullsize image: https://s3-us-west-1.amazonaws.com/h...r_fullsize.jpg
Natural gas bus with gas bags - photo
1917 natural gas-powered taxi - photo
2003 Rinspeed Bedouin natural gas powered car - photos
Wood gas cars - photos