From the June 1930 issue of Modern Mechanics:
Automatic Food Cooker Runs by Exhaust Heat of Car
Meals can literally be cooked on the run through the use of the automatic cooker shown in the photo above. The cooker is mounted on the rear bumper of the motor tourist’s car and an extension from the exhaust pipe connected up with it, as shown in the insert. The cooker contains a steam pressure kettle which is heated by the hot exhaust gases. An hour’s drive is quite sufficient to thoroughly cook meats and vegetables. Total weight of the unit is so slight that running qualities of the car remain quite unaffected. Motor tours are much more pleasant when one is assured of a well-prepared meal at the end of the trip.
Thanks to the Los Angeles Master Food Preservers for the tip on this oddball bit of history.