I had one of them for years and they are power HOG's, i would not use one in the truck unless i was running the motor(over the road driver). You will have burnt food in the middle of the lower pan, this is the only heat source, I have in the past heated caned food with mine, not more then 30.
I have cooked things like a small roast and pork chops in mine , but you have to use something to hold the food off the bottom, i used foil bunched up to make a an over curved S.
There is a newer model out now Amazon.com: Max Burton 12 Volt Lunch Box "Stove To Go" Digital Cooker: Everything Else
Happy cooking, and yes this is a power hog as well, this one has anon stick removable pan......... Fair Winds