The alternative to all those block-heater plugs is keeping a truck running all bight to boost all the others in the morning -- normal practice with military-pattern vehicles when I was a tad.

My old VW diesels were cruelly dependent on the block-heater in winter, but I haven't had to boost a car even at minus 30 since the modern VW turbo-diesels came in. You can't even install a block-heater in a 2011 Golf TDI -- fact!