Good point about the MRE heaters, they throw quite a bit of gas. (Both during cooking, and after eating <img src="/images/graemlins/blush.gif" alt="" />) I'm always using them outdoors when camping, so it's not a problem, but, in a car it might be. (The hydrogen anyway, your mileage may vary on the methane you need to deal with later...)

Another option, if these suit your fancy, are Mountain House style freeze dried backpacking foods. They now make a flameless heater for them also. It's a little different than the MRE heater, but, they still just need water to activate.

http://www.mountainhouse.com/data/new_prdcts.html#oven

I have a couple Full Meal MRE packs with heaters in the trunk, so that gives you a main course, side, snack, drink, and a spoon, wet nap, coffee mix, gum... You only get one heater with the MRE's, so if you want to heat your Country Captain Chicken, AND heat your mashed potatoes, you might want an extra MRE heater. You can try to jam both packs close to eachother in a box or wrapped in something, but, the MRE heater is really just designed for one packet at a time.

Having said that, I also have a brick of Datrex rations in the trunk bag. If I am forced to eat on the move, it's a lot easier to choke down a couple of those ration cookies than stop to eat the MRE's. Sitting in the car though, I'd go for the MRE first! The MRE's usually have an energy bar or some other type of snack in them also.