Wouldn't a super-insulated engine block be nice? If it could hold a good percentage of the residual heat for up to 24 days and not be too heavy it would certainly be ideal for those of us in northern climates. Where's the asbestos when you need it?
I used to use a 1000 watt car space heater in my Fiesta ages ago when we got real winters. Without it, the doors wouldn't open.
What would be nice is if a space heater, block heater, battery charger, outdoor temperature sensor (which is already on all cars with TPMS) and a timer control could all be integrated right into new cars. As you shut the car off at night, you tap 7am on a console control and plug it in. It monitors the temperature of the interior, block and outside temperature and has the car ready at 7am for you. Sherrazhell beats all the remote starters that are way too prevalent around here.