I was up on a job in North Dakota when the temps dropped to -20f. My gasoline powered van started up just fine but I have no idea if that would work if the temps dropped another 20 points. The diesel powered generator at work failed to start, the boss had to turn back because the heater in his truck froze up, one guy had a frozen radiator on his pickup and blew up his engine so the remaining vehicle was used to tow it to the shop. After an hour I realized no one was coming out to the job site so I left.