[Caper11]

Dodge has a good proven summential cab heater it more like a furnace it's made by espar i've thought about one myself, This is the same on used in big trucks Its diesel fired and will keep the cab warm while the engine is off. I 'm not sure if dodge offers espars engine heater. I don't know what the other brands are offering.
What brand are you looking at? I'm pleased with my fuel milage with mine so far considering the DPF on the exhaust, But I only have 13000km on mine so far and the milage is improving slightly, I don't regret my purchase now,( I did at first) I understand how the emmisions system works now and with some updates done and it not a big deal I get almost 20mpg unloaded during the winter, which is not bad concidering the fuel that gets dumped into the exhaust to clean the DPF during the colder months