Is it illegal or cruel to leave a dog crated comfortably in an SUV?

I've heard both of these answers. Firstly, I am on my third Siberian Husky and my first two could stay outside in temps in the teens. At home I have a doggy door and they prefer to lay out on the deck in that kind of weather. Secondly, I only do this when I go to work in extreme cirstances. I park in a gated parking lot at work and crack the windows open. Thirdly, my new rescued pup(10 months) is still in crate training stages and I'm trying to build up his tolerance to time in the crate. Anyways, the temps are usually 60 and below, although lately in the 30's. I can make it to the car to take him out at least twice throughout the day to let him stretch his legs and go to the bathroom. What are your thoughts on this. I don't see the difference in leaving huskies tethered to a stake or even outside in a kennel, which many sled dogs are, or even crated in a house. I wanna know what all the fuss is about.