The best type of car food warmer for people with short commutes is a car microwave. Unlike traditional car food warmers, car microwaves can heat up or cook food fast. Of course, they also take a lot of juice. You’ll typically have to wire a microwave into the fuse panel or directly to the battery (with an in-line fuse) due to the amperage requirements, and running a device like this with the engine off is a great way to to the point where you car won’t start back up.
If you want to heat up food on shorter trips, then most car food warmers won’t do the trick. In that case, you may want to look for a dual power AC/DC unit that runs on either 12V DC or 120V AC. That will allow you to get your lunch started on your commute, then plug it into the wall at work and have it ready for lunch. Of course, you can always just wire in a car power inverter and use a travel-sized food warmer that only runs on 120v AC.