Block Heater

I've been wondering what the Block Heater is in the boot of the rental. Well, I think I've figured it out...at each of the parking bay's at the hotel, there is a stanchion with 2 electrical sockets - I initially thought this was for electric vehicles, but now I've realised it must be to plug the Block Heater in...I note the weather forecast has it down to something like -15 later this week...might need it!