Originally Posted by Double-Trinity

Actually, this is another potential benefit of a plug-in hybrid, the car itself could have the built-in block heater, with timers, and warm the engine as well as charge the batteries. Any extra regenerative braking power that could not be charged into the battery could be dumped into the engine-heater wires to act as a big resistor, if warm-up is needed, as well. This would save the brakes more, and heat the engine faster in cold weather. That would be quite important actually as the plug-ins woudl need to start and stop the engine much more frequently due to having more aggressive electric "assist", they'd also have more of a tendency to "cool off" in that time, and running at idle when all the power, save for hard accelerations and high-speed steady-state cruising, is coming from the electric motor would be a waste.